8^th International Conference and Exhibition on Lasers, Optics & Photonics Nov 15-17, 2017 Las Vegas, Nevada, USA

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A G Unil Perera has received the BS degree in Physics (with first class honors) from the University of Colombo, Colombo, Sri Lanka and an MS and PhD degrees from the University of Pittsburgh. He is currently a Regents’ Professor at the Department of Physics and Astronomy, Georgia State University, Atlanta. He is a Fellow of the IEEE, SPIE and APS. He has 8 US patents, 4 edited books, 11 invited book chapters and over 180 publications. He is also a Member of the Editorial Board for the IEEE Journal of Electron Device Society.

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Multi-band photodetectors have received increased attention over the years due to their wide applications in civilan, commercial, medical and military sectors. The photodetectors based on III-V semiconductor heterostructures have been studied extensively for multi-band detection, covering ultra-violet (UV) to far-infrared (FIR) region. Due to material system maturity, GaAs/AlxGa1-xAs heterostructures provide an attractive option demonstrating photodetection covering UV-FIR range. In more recent studies, the conventional spectral threshold limit, that is, λt=hc/Δ set by the minimum energy gap Δ, has been overcome owing to a novel detection mechanism arising from the hot-carrier effect in the asymmetrical p-GaAs/AlxGa1-xAs heterostructures. It has been experimentally demonstrated that a detector with a conventional spectral threshold of ~3.1 μm shows an extended wavelength threshold of up to ~68 μm. In addition to the munti-band detection capability, an important advantage of the wavelength extension mechanism is a lower dark current of the dectctor, which is determined by standard Δ and is evident from close agreement of the experimentally measured dark current data to the theoretical fits based on 3D carrier drift model. Therefore, the wavelength threshold extension mechanism makes it possible to design a detector with its dark current being much lower compared to that of a detector without the extension mechanism. Based on the these studies, the of III-V semiconductor heterostructures offer potential for multi-band detection from UV to FIR by utilizing appropriate detector architectures.

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Bellet Daniel is an Assistant-Professor at Grenoble University in 1990 and is Professor at Grenoble INP since 1998. He was Junior Member at IUF (French institution to promote excellence in research) in 1999 and is now the Director of the Academic Research Community “Energies” at the Région Rhône-Alpes since 2011. His research is focused on material physics and more specifically now on transparent conductive materials. His works are two-fold aims: fundamental as well as integration of transparent electrodes in devices. He has co-authored more than 120 peer-reviewed publications or proceedings, 8 book chapters and has 28 as h-index.

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There has been lately numerous researches devoted to nanostructured transparent electrodes, which play a pivotal role in many modern opto-electronics devices such as solar cells or light-emitting devices. Currently, ITO (Tin-doped Indium oxide), the most commonly used material, suffers from two major drawbacks: indium scarcity and brittleness. This contribution aims at briefly reviewing the main properties of transparent electrodes (TE) as well as the challenges which we still face in terms of efficient integration in devices for several technologies. A more specific focus will be devoted to two promising TE. First, the emerging transparent electrodes based on silver nanowire (AgNW) networks, which appear as a promising substitute to ITO with excellent optical and electrical properties fulfilling the requirements for many applications including flexible devices. In addition, the fabrication of these electrodes involves low-temperature processing steps and upscaling methods, thus making them very appropriate for future use as TE for flexible devices. Their main properties, the influence of post treatments or the network density and nanowire size but as well their stability will be discussed. The second studied TCM is based on Fluor-doped Tin Oxide (FTO) which exhibits interesting opto-electronic properties. We will show that a rather promising TE can be fabricated from S:TiO2-FTO nanocomposites which shows tuneable high haze factors from almost zero to 60% by using a simple and cost effective method. The resulting optoelectronic properties of such TE appear very well suited for its efficient integration into solar cells.

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Kaddour Lekhal received his PhD in Physics - Material Science from the University Blaise Pascal (France) in 2013 followed by Post-doctoral training at National Center for Scientific Research (CNRS). He is currently working as a Researcher at Amano lab., Nagoya University. His work focuses on the synthesis and characterization of nanostructures, particularly the growth of long III-V semiconductor nanowires by HVPE and MOVPE. He is deeply interested in developing new devices using long nanowires for LEDs, LDs and solar cells. He has published more than 30 papers in reputed journals.

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One‒dimensional (1D) nanostructures-nanowires have shown promising potential to improve the device performance, such as high-efficiency LEDs. The growth of semiconductor nanowires was discovered for the first-time by Wagner and Ellis in 1964 through the vapor‒liquid‒solid (VLS) mechanism. Since then, this method has become widely used for synthesizing  semiconductor nanowires. However, the growth of III‒nitride nanowires with controlled orientation is challenged limited by the nature of the catalyst or the substrate used for the growth. The control of following parameters is important for large-scale integration of nanowires into practical devices: the vector (x, y) on a plane, orientation (ψ), length (L) and diameter (d). First, the growth mechanism based on nucleation theory and key issues related to the growth of III-nitride semiconductors nanowires will be presented. After that, some solution will be proposed to grow GaN nanowires with controlled orientation by using VLS approach or selective‒area‒growth (SAG) approach. We show that GaN nanowires grown on sapphire substrate with VLS approach can be controlled by tuning the atomic percent ratio of Au to Ni in HVPE environment. Pure Ni catalyst resulted in the growth of single-crystalline horizontal GaN nanowires, whereas mixture Au/Ni catalyst resulted in the growth of inclined nanowires with exceptional length and defect-free structure. Subsequently, we focus on the growth of GaN nanowires by SAG-MOCVD on silicon substrates; in particular we are interested to control the direction by inserting an orientation-induced buffer layer deposited by a directional sputtering before the nanowires growth. Highly ordered nanowires along the surface normal direction to parallely inclined GaN nanowires were obtained. HR-TEM and photoluminescence measurements indicated that the nanowires not only are free from structural defects (stacking faults or dislocations) but also have a good optical quality regardless of the orientation. Field effect transistors (FETs) based on horizontal nanowires have been fabricated by using conventional photolithography. The FETs exhibit reasonable electrical properties similar to other vertical nanowires, confirming the good structural quality of our nanowires. This example highlights the potential of the controlled oriented nanowires for the large-scale integration into practical devices.

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Yu Zheng has completed his PhD in the year 2012 from Central South University. He is the Associate Professor of Central South University. He has published more than 50 papers in reputed journals and has more than 30 patents in China. His current research interest is precision engineering, precision motion control and optoelectronic device packaging.

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Optoelectronic devices are the foundation of optical fiber communication system and optical fiber sensor system. With the development of optical fiber communication, alignment and between planar optical waveguide chip (POW chip) and optical fiber array (OFA) have become the focus of many industries. In general, the alignment is performed passively and actively. During passive alignment, the two optical components may be placed according the expected desired orientation. Machine vision can be used in passive alignment to locate the position of the two optical components, then used to guide the movement of the motor stage for the alignment. Optical component edge detection is one of the key steps of machine vision in alignment. This paper has proposed a line detection algorithm based on the progressive probabilistic Hough transform (PPHT) and iteratively reweighted least squares (IRLS) algorthm for alignment between planar optical waveguide chip and optical fiber array. The experiment results show that the detection angle error is less than 0.005º and the time consumption is less than 0.5 s through the proposed algorithm. Besides, it also can accurately fit optical component edge with some non-random factors. Therefore, the proposed new algorithm has the advantages of high precision, fast computing speed and good robustness and it can successfully realize the high-precision fast line detection of optical component edge.

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S Nitta obtained his PhD in 2003 from Meijo University, Japan. Since then, he has been developing MOVPE equipment and high-efficiency blue and white LEDs at companies. In 2015, he joined Nagoya University as a designated Associate Professor. His research is focused on the epitaxial and bulk crystal growth of nitride semiconductors and their applications to future optical and electronic devices.

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More compact, lighter and long lifetime mobile devices and more environmental friendly power supplies are being developed by utilizing nitride semiconductors such as AlN, GaN, InN and their alloys. Together with high-efficiency InGaN blue light emitting diodes (LEDs), high-spec and long-lifetime portable devices and general lighting will play an important role in a sustainable modern 21st century society. AlGaN/GaN high electron mobility transistors have been used in new-generation mobile communication bases, delivering more data with lower consumption. Finally, ultraviolet LEDs are widely used for curing and germicidal disinfection. The potential of nitride semiconductors is not limited to these applications, but to achieve their potential, optics can help a lot. High-quality, high-indium-content InGaN is a prerequisite for long-wavelength visible emission from green to red. However, InGaN is difficult to grow with higher indium content because of the lattice parameters and growth conditions mismatch between GaN and InN. Indium fluctuation and strain relaxation introduced by morphological degradation are substantial challenges. In order to monitor crystal properties and surface evolution during growth, we used a three-wavelength laser beam scattering in situ monitoring system on a horizontal metalorganic vapor phase epitaxy reactor. For electronic devices, ex situ emission microscopy is a powerful tool for the analysis of critical defects on vertical GaN power electronic devices. The optical emission image of a biased device reflects leakage information and allows us to identify the properties of defects.

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Si-Young Bae has completed his PhD from Gwangju Institute of Science and Technology (GIST) in South Korea and his Post-doctoral studies from Nagoya University, Institute of Materials and Systems for Sustainability (IMaSS) in Japan. He is currently working as a Researcher of IMaSS in Nagoya University. His research interests have been focused on crystal growth and characterization of III–N wide bandgap compound semiconductors for optoelectronic device applications. He has published more than 25 papers in reputed journals.

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Pulsed-mode growth in metal-organic chemical vapor deposition (MOCVD) has provided us attractive means to obtain homogeneous and elongated nano rod array in GaN epitaxy on heterosubstrates. Nowadays, ultra-elongation behaviors of pulsed-mode growth give rise to potential of growing single crystalline GaN on extremely challenging substrates such as Si(001) and amorphous substrates. Our finding in such harsh epitaxy has indicated that high quality of GaN nanorods can be achieved above the critical height (~500 nm) from the bottom of nanorods, while many structural defects are observed at the interface between the GaN nanorod and the heterolayers. Obviously, the  dislocation density of epilayer is highly dependent on the lattice mismatch of the grown layers. In this presentation, we compare these structural imperfections of several hetero-substrates, e.g., sapphire, Si and amorphous quartz. Especially, we focus on the basal stacking faults (BSFs) of GaN nano rods, which were tremendously suppressed, compared to conventional epi-layers. The reduction and corresponding type of BSFs were identified by observing X-ray diffraction, thereby quantitatively proving the suppression of the crystal imperfection with selective-area growth. Moreover, to take into account the behaviors of BSFs in GaN nano rods, high-resolution transmission electron microscopy and low-temperature photoluminescence measurement were carried out. The suppression of BSFs in GaN nano rods were clearly observed by identifying defect-related luminescence peaks in the optical characterization. Therefore, the localized stain of nano architectures can provide better platform of crystal growth to overcome typical defects generated in the conventional epitaxy and finally enhance the efficiency of optoelectronic
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Kenji Murakami has completed his PhD in the year 1983 from Osaka University, Japan. He is working as a Professor in the Department of Engineering, Graduaate School of Integrated Science and Technology, Shizuoka University. He has published seven book chapters, more than 100 papers in reputed journals and has been serving as a Referee of reputed journals.

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Mechanoluminescence (ML) is a phenomenon where light emission is induced by a mechanical action on a solid. The ML is classified into fracto-, plastico- and elastico-MLs according to an excitation mode of the electrons. When the material structure is fractured then the electrons are excited to the higher energy levels followed by the relaxation process of electrons to lower energy levels. The energy difference is released as a light. This kind of luminescence is observed as a result of the plate force during and just earlier to earthquake. The ML was also detected by a peeling of the tape in a vacuum. We have synthesized the europium doped dibenzoylmethide triethylammonium as an organic mechanoluminescent material. The synthesis was completed at a very low temperature of 70°C by a controlled slow cooling method. The synthesized material showed a very strong mechanoluminescence at 612 nm in the visible region. In this study, the ML material has been synthesized with an addition of 1-ethenylpyrrolidin-2-one [(polyvinylpyrrolidone) (PVP)]. We have investigated effects of the ligands, EuI2, EuBr2 and EuCl2 on the ML substance structure, molecular orbital electron distributions of the ligands and the ML and the photoluminescence. The ML material structure was characterized by using the nuclear magnetic resonance spectroscopy (NMR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Gaussian DFT/B3LYP/6-31G (d,p) software. The ML properties were observed by using the multichannel spectroscope.

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Devki N Talwar graduated from Allahabad University in India in 1976 with a PhD degree in Condensed Matter Physics. From 1977-80 he worked as a Visiting Scientist at the Commissariat a’l Energie Atomic, Saclay, Gif-sur-Yvette, France with M Vandevyver. While at Saclay he collaborated with theoretical /experimental group of M Balkanski, including Karel Kunc, M Zigone and G Martinez and supervised three PhD theses. In January 1980 he joined the Physics Department, University of Houston as a Visiting Professor and collaborated with P C S Ting on problems related to the electronic properties of defects in semiconductors and supervised a PhD student. From 1982-87 he was a Faculty at Texas A & M University. He joined the Physics Department at Indiana University of Pennsylvania in 1987, supervised 20 MS theses. Since 2007-2014, he has served as the Chairperson of the Physics Department.

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Comprehensive experimental and theoretical studies are reported to assess the vibrational and structural properties of 3C-SiC/Si (001) epilayers grown by chemical vapor deposition in a vertical reactor configuration. While the phonon features are evaluated using high resolution infrared reflectance (IRR) and Raman scattering spectroscopy (RSS)–the local inter-atomic structure is appraised by synchrotron radiation extended x-ray absorption fine structure (SR-EXAFS) method. Unlike others, our RSS results in the near backscattering geometry revealed markedly indistinctive longitudinal- and transverse-optical phonons in 3C-SiC epifilms of thickness d<0.4 μm. The estimated average value of biaxial stress was found to be an order of magnitude smaller while the strains were two-orders of magnitude lower than the lattice misfits between 3C-SiC and Si bulk crystals. Bruggeman’s effective medium theory was utilized to explain the observed atypical IRR spectra in 3C-SiC/Si (001) epifilms. High density intrinsic defects present in films and/or epilayer/substrate interface were likely to be responsible for (a) releasing misfit stress/strains, (b) triggering atypical features in IRR spectra and (c) affecting observed local structural traits in SR-EXAFS.

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Juan Carlos Rendón-Angeles has received his degree of PhD in Engineering from the Faculty of Mechanical Engineering, Tohoku University Japan (1997). His early career holding a Postdoctoral position (1997-2000) at the Research Laboratory of Hydrothermal Chemistry enabled him to study the basic fundamental chemistry of the mechanisms related to hydrothermal reactions. He has joined the Department of Ceramic Engineering at CINVESTAV Saltillo Campus in 2000 and was promoted to Associate Professor in 2009-at present. He has published more than 50 papers in reputed journals and has been serving as an Reviewer of reputed journals.

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The present experimental work relates to a study of the hydrothermal powder processing of a functional luminescence compound. Strontium molybdate, strontium tungstate and their solid solutions were successfully prepared under hydrothermal conditions. The soft chemical method studied comprises the usage of SrSO4 (celestite) ore as the precursor of Sr. Particle crystallisation occurred rapidly because of a single step reaction, which was promoted using a highly concentrated alkaline media (5 M NaOH solution) at a temperature below 200ºC for 2 h under vigorous stirring at 130 rpm. In all the cases investigated, the particle crystallisation took place without the formation of secondary phases, while the ionic species representing impurities in the precursor mineral remained dissolved in the alkaline fluid. Differences in the morphology of the particles were observed when the W content varied from 25 mol% and 75 mol%. Additionally, the mechanism associated with the reaction and precipitation process investigated is discussed in detail, together with a crystalline structural characterization. Photoluminescence analyses indicate that blue and green emission responses and its intensity can be attenuated when incorporating W contents between 10 mol% and 60 mol%. Structural analysis conducted by Rietveld refinement and FT-Raman methods indicated that a localized distortion of the MO4 tetrahedral site of the scheelite structure is produced by the disordering of the Mo and W ions resulting in the blue and green emission attenuation. Hence, these present results indicate the intermediate SrMo1-XWXO4 particles have a potential to operate as a phosphorous-like light emitting material.

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Hao-Hsiung Lin received his PhD degree from National Taiwan University in 1985. He has been working as a Professor with the Department of Electrical Engineering at National Taiwan University since 1992. His research interests are on the MBE growth of dilute nitrides, mid-infrared semiconductors and nano-hetero-epitaxy of compound semiconductors. He has published more than 170 papers in reputed journals. He is a Member of the Chinese Institute of Engineers and a Senior Member of IEEE.

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InAs nanowires grown on Si are promising and have attracted a lot of attention since its potential in applications to electronic and optoelectronic devices on Si platform have been deciphered. The small contact area of the nanowires is able to mitigate the large lattice and thermal mismatches in between InAs and Si. However, the orientation control for InAs nanowires on Si is an issue for the growth. Basically, the axial direction of InAs nanowire is along the predominate <111>B family. The non-polarity of Si further complicates the issue and allows four <111>B directions for InAs nanowires on either (001) or (111) Si substrate. To control the direction of InAs nanowires on (001) Si, we propose a two-step growth method utilizing the shadowing effect in MBE growth to grow InAs nanowires from a SiO2/Si nanotrench structure. In the first step, we aligned the In beam with the longitudinal axis of the trench. Due to a shadowing effect resulting from one trench wall, InAs nucleated on the opposite trench end. In the second step, the growth proceeded with substrate rotation to elongate the nanowire. Because the trench was along [-110], the narrow trench width effectively blocked the growth of InAs nanowires perpendicular to the long axis of the trench. In this manner, we were able to control the growth direction. Up to 94% of the nanowires were along the desirable direction. Cross-sectional TEM was used to investigate the structural properties of the nanowires as well as the growth mechanism of nanowires and clusters in the trenches. We found that the nanowires developed from Si residue at the trench end with low misfit dislocation density. While the cluster developed at the center of the trench has high misfit dislocation density at InAs/Si interface. Details of the growth mechanism will be presented.

Biography:

Masafumi Jo has received his PhD from the University of Tokyo in 2003. He is the Researcher of Quantum Optodevice Laboratory at RIKEN. He has worked on fabricating nano-structured solid-state light sources.

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AlGaN deep ultraviolet light-emitting diodes (DUV-LEDs) and laser diodes (LDs) are attracting a great deal of attention, since they have the potential to be used in a wide variety of applications, such as for sterilization, water purification, UV curing and in the Medical and Biochemistry fields and so on. As a result of recent developments in AlGaN DUV LEDs, high internal quantum efficiencies (IQE) of more than 60-70% have been achieved by reducing the threading dislocation density (TDD) of the AlN, by improving the crystal growth technique and/or by the introduction of AlN single crystal wafers. However, the wall-plug efficiency (WPE) of AlGaN DUV-LEDs still remains at several percent. The first target for the efficiency of AlGaN DUV-LEDs is to go beyond an efficiency of 20%, which would make them comparable to mercury lamps. In this work, we demonstrate an external quantum efficiency (EQE) of over 20% in an AlGaN DUV-LED by a significant improvement of light extraction efficiency (LEE). In order to increase LEE of DUV LEDs, we introduced a transparent p-AlGaN contact layer, a highly reflective p-type electrode and AlN template buffer fabricated on patterned sapphire substrate (PSS). By introducing transparent p-AlGaN contact layer and reflective electrode, LEE was enhanced by approximately 3 times. We also tried to increase wall plug efficiency (WPE) by reducing the applying voltage that was increased by increasing p-AlGaN contact resistance. By optimizing p-AlGaN layer structures, we have succeeded in reducing the operating voltage of DUV LED and obtained record WPE of 9.6%.

Biography:

Doron Cohen Elias has completed his PhD from Technion, Israel Institute of Technology. From 2012 to 2014, he was a Post-doctoral at the University of California Santa Barbara (UCSB). Since September 2014, he is a Research Scientist with the Nuclear Research Center, Soreq (Soreq NRC). He has published more than 30 publications in reputed journals and conferences.

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Extended short wave infrared (eSWIR) photodetectors are used in night vision applications which detect reflected night glow and black body radiation. They also detect atmospheric gases which have high absorption coefficient between 2.5 and 3 μm wavelengths. Type II superlattice (T2SL) epi-structures grown on GaSb and InP substrates, with flexible cut-off wavelength ranging between 2 to 3 μm and a homogenous InPSb layer, lattice matched to a GaSb substrate, with a photoluminescence peak at 2.9 μm, are candidate technologies for eSWIR detectors. In this study, we fabricated and characterized photodetectors based on three different technologies: T2SL InAs/AlSb, T2SL InGaAs/GaAsSb and InPSb. The epi-grown layers were characterized using photoluminescence (PL) and high resolution XRD (HRXRD) tools and the photodetectors performances were measured and compared using semiconductor device parameter analyzer, Fourier transform infrared (FTIR) and Black Body tools.

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Takayoshi Katase is currently working as an Associate Professor of Laboratory for Materials and Structures at Tokyo Institute of Technology, Japan. He obtained his BS from Tokyo Institute of Technology, Japan in 2007 and MS from Tokyo Institute of Technology, Japan in 2009 and a PhD from Tokyo Institute of Technology, Japan in 2012. In 2012, he worked as a Post-doctoral Researcher in FIRST Program, JSPS. In 2012, he worked as an Assistant Professor of Research Institute of Electronic Science, Hokkaido University, Japan. In 2016, he worked as a Researcher in PRESTO (Scientific Innovation for Energy Harvesting Technology), JST, Japan.

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Using the flexible valence state of transition-metal ions in transition metal oxides (TMOs), the optoelectronic properties can be largely controlled through the electronic phase transitions. Protonation of TMOs is one of the modulation techniques because the proton in TMOs acts as shallow donors to donate an electron into TM cations, resulting in a dramatic change in the optoelectronic properties. However, the protonation needs high-temperature heating process or electrochemistry in liquid electrolyte and thus it has not been suitable for the device application. In this talk, we propose a new approach of RT-protonation of TMOs by using a solid-state thin-film-transistor-type structure with “liquid- leakage-free water”, in which water is infiltrated in a nanoporous glass, as the gate insulator and demonstrate the RT-protonation-driven infrared (IR) transmittance tunable metal-insulator conversion device by using a thermochromic vanadium dioxide (VO2) as the active channel layer. Alternative positive and negative gate-voltage applications induce the reversible protonation/deprotonation of VO2 channel and the double-digit sheet-resistance modulation and 49% modulation of IR-transmittance were simultaneously demonstrated at RT by the metal-insulator phase conversion of VO2 in a non-volatile manner. The present device is operable by the RT-protonation in all-solid-state structure and thus it will provide a new gateway for the development of functional optoelectronic devices.

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Geoffrey Avit has completed his PhD in the year 2014 from Blaise Pascal University. He is currently a Post-doctoral Reseacher at Institut Pascal (France), a leading laboratory in the field of HVPE growth of III-V nanostructures.

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III-V semiconductors have a direct bandgap that can be tuned through alloy engineering and therefore appear as very interesting for solar-cells, solid-state lighting and high power applications. The performances of current devices may be increased through the use of nanostructures and nanowires which look promising for the integration of high efficiency devices. Nanowires exhibit great properties such as efficient strain relieving capability and large specific area. Growth on silicon substrates and core-shell structures can be considered as well. Still, the production of nanowire-based devices faces material challenges related to morphological, structural, optical and electrical properties which are very much linked to the synthesis process. This presentation will focus on hydride vapor phase epitaxy, which is a growth process implemented in a hot wall reactor using chloride precursors and showing unique features regarding the growth of III-V and III-nitride nanowires. For example, self-catalyzed GaAs nanowires were grown on silicon at a faster growth rate (60 μm.h-1) exhibiting a constant zinc-blende crystalline phase, for the potential fabrication of GaAs-based photonic devices on Si. For III-nitride materials, InGaN nanowires demonstrating the entire composition range were grown by using a method compatible with the standard GaCl-based GaN growth process. Photoluminescence coupled with transmission electron microscopy measurements showed that these nanowires could overcome the so-called green gap and stretch the limits of solar cells efficiency. By taking advantage of the large growth rates anisotropy resulting from the use of chloride precursors, we could freely tune the shape of GaN wires on masked substrates with (sub)-micrometric apertures.

Biography:

John G Ekerdt earned his PhD from the Univerisity of California, Berkeley in 1979. He is currently working as the Associate Dean for Research in Engineering and the Dick Rothwell Endowed Chair in Chemical Engineering at the University of Texas at Austin. He has more than 300 refereed publications, two books and seven US patents. His current research interests focus on the surface, growth and materials chemistry of metal, dielectric and perovskite fi lms and nanostructures by developing and understanding the reactions and chemistry that control nucleation and growth of fi lms and nanostructures.

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Characterization of low density sites on planar oxide surfaces remains a challenging task. Such sites are believed to play an important role in catalysis and particle/fi lm nucleation, although the inability to directly observe these sites limits our understanding of these processes. We have developed a technique that enables detection of low density sites on planar surfaces using fl uorescent probe molecules. Derivatives of perylene, a high quantum yield fl uorophore, with various functional groups were used to titrate surface sites in vacuum. Th e functional group was chosen to chemically bind to the desired site and in situ photoluminescence (PL) measurements were used to determine the density of sites and learn about their distribution. An estimated detection limit of <1010 sites/cm2 is possible with this technique. We shall discuss our work using fl uorescent probes to study sites on the silica surface. In particular, results of our studies of strained siloxane (density~1012 cm-2) with perylene-3-methanamine and oxygen vacancy defect (OVD) sites (density~1011 cm-2) with 3-vinyl perylene will be presented. Particle nucleation on oxides is suspected to involve defects that trap adatoms and form critical nuclei. Using this technique, the role strained siloxane and oxygen vacancy sites play in trapping adatoms during the nucleation of germanium and ruthenium particles on silica surfaces is examined.

Biography:

Kuniharu Ijiro received his Doctor of Engineering degree from Tokyo Institute of Technology, Japan in 1991. He worked as an Alexander von Humboldt Foundation Research Fellow at Ringsdorf’s group in Johannes Gutenberg University Mainz, Germany. He is working as the Professor and concurrently the Deputy Director of the Research Institute for Electronic Science (RIES) and the Professor of the Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University. He is interested in biomimetic self-assembly of nanomaterials and polymers to create novel functions.

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Surface-enhanced Raman scattering (SERS) is a promising approach for the label-free detection of molecules. Th e morphology of metal nanostructures is a primary factor determining the magnitude of signal enhancement on Raman scattering. In general, a narrower gap can form a stronger electromagnetic fi eld, but it makes insertion of analytes into a hot spot more diffi cult. Th is is a trade-off when using conventional SERS substrates. We have fabricated tunable plasmonic nanostructures, the gap distances of which can be controlled by the salt concentration, through the formation of gold nanoparticle self-assembled thin fi lms on solid substrates and their transfer onto poly-acrylic acid gel. Th e extinction spectra shift ed reversibly with volume change of the gel according to the degree of swelling. When the target molecules were injected onto this substrate as the gaps were opened (widened) and SERS was measured aft er the gaps were closed (narrowed), the signals became stronger than that observed without any gap control. Th is method can be served for the sensing of macromolecules such as proteins.

Biography:

Tatsuo Shiina received his BE, ME and DE degrees in Electrical Engineering from Science University of Tokyo, Tokyo, Japan. He is working as an Associate Professor at Graduate School of Advanced Integration Science, Chiba University. He studies near range compact lidar for disaster prediction, portable OCT for industrial use and beam propagation in random media.

Abstract:

Beam propagation has been given strong attention in a variety of applications that is, medicine, remote sensing and information science. Especially, the beam propagation in highly scattering media, which is called random media, gathers highly emotion to control from the past to the present. In general, the multiple scattering gets rid of beam characteristics such as intensity distribution, phase front and polarization. In this study, self-converging eff ect of a polarized annular beam was applied in random media. The collimated annular beam of a few tens millimeters takes a few hundred meters to transform its beam shape into the non-diff ractive beam in air, while this transformation was shorten only to less than a few tens centimeters in random media with a certain concentration. The generation condition of the non-diff ractive beam in random media is not only the incident beam and the media characteristics, but the obserbation condition is also important. Th e specialized detector was installed with narrow fi eld of view in our experiment. Th e detected beam has its optical characteristics of the non-diff ractive beam. It has the center peak and side rings in optical axis and keeps its waveform in its propagation. Media concentration and propagation distance control the generation and the waveform of the non-difractive beam. The center peak of the non-difractive beam has the unique behavior due to the media concentration. The is study indicates the generation of the non-diff ractive beam in random media, its waveform structure on the isotropic multiple-scattering and the unique behavior of the alternative change of its waveform.

Biography:

Giedre Samuoliene has completed her PhD from Aleksandras Stulginskis University (Biomedical Sciences, Agronomy). She is the Chief Researcher of Laboratory of Plant Physiology and the Deputy Director for Research of Lithuanian Research Centre for Agriculture and Forestry, Institute of Horticulture and Lector at Aleksandras Stulgisnkis University. She has published 25 in ISI WoS data base journals with impact factor, 24 publications in ISI WoS data base journals without impact factor. She received National Science Award (2014, with co-authors), Silver Medal of Vytautas Magnus University (2015) and Scholarship of the Lithuanian Academy of Sciences (2012-2013).

Abstract:

Advances in light technology are rapidly developing, the light-emitting diode (LED) technology as supplementary light in greenhouses, phytofactories or other closed environment growing chambers is a powerful tool for purposeful and appropriate plant cultivation. LED lighting, due to its technical possibility to control dynamic or continuous light spectrum, intensity, frequency of each component and period is useful for research applications, as well as such lighting is useful for growers, due to energy saving properties. The  development of agronomic research ensures the public demand for vegetable food, feed and industry raw materials. Plant physiology is considered to be theoretical background for agronomy (crop production and horticulture). Knowledge of plant physiology patterns and management of crop photosynthetic indices by technological tools enables to control formation of productivity elements and quality of production. Moreover, response to light is not a simple linear signal transduction pathway, but it is integrated information outcome of various photoreceptors, which act through complex network of interacting signaling components. The is enables to induce weak photo stress in purpose to manipulate plant antioxidant potential. The us, such plant physiologycal researches allows to know plant functioning mechanisms, control processes of growth and development, realize potential of biological productivity. The opportunity to control processes of growth, biological productivity and nutritional quality using traditional high-pressure sodium and/or innovative light-emitting diode lighting will be presented.
 

Biography:

Dong Li has completed his PhD from East China Normal University. He is the Assistant Researcher of Microsystem and Terahertz Research Center. His research interests include quantum metrology and quantum interferometry.

Abstract:

One common tool for precision measurement is interferometer. Compared with the conventional SU(2) interferometer, the SU(1,1) interferometer utilizes parametric amplifi ers for wave splitting and recombination. Due to parametric amplifi cation process, SU(1,1) interferometers have a better phase sensitivity than SU(2) ones under the same condition of input states. With squeezed vacuum input, the phase measurement sensitivity of SU(1,1) interferometers can be improved. The is improvement is due to noise reduction. Here, we theoretically study parity detection on an SU(1,1) interferometer with coherent mixed with squeezed vacuum input states. Parity detection counts the evenness or oddness of the photon number in one output mode. Our work shows that parity detection reaches below Heisenberg limit when the input coherent and squeezed vacuum light are mixed in roughly equal proportions with a strong parametric amplifi er strength. Compared with homodyne detection, parity detection has a slightly better phase sensitivity with coherent and squeezed vacuum inputs and parity detection is more suitable than homodyne detection in some certain situations. Lastly, we also investigate the Quantum Cramer-Rao bound for SU(1,1) interferometers, showing that phase measurement sensitivity does not surpass Quantum Cramer-Rao bound even though it surpasses Heisenberg limit. Parity detection was initially proposed to applied with input N00N states and Fock states in SU(2) interferometers. Now, parity detection invades SU(1,1) interferometers.

Biography:

Hua Guan has completed his PhD from Wuhan Institute of Physics and Mathematics (WIPM), The Chinese Academy of Sciences (CAS) and he visited NIST Boulder twice between 2008-2010. He is a Professor of WIPM. His major is Precision Measurement Physics. And his research interests are single-ion optical clocks and trapped ion precise spectroscopy. He has published more than 20 papers, including Phys. Rev. Lett., Phys. Rev. A, Appl. Phys. B, Rev. Sci. Instum. etc.

Abstract:

A comparison of two optical clocks and a detailed study of the systematic frequency shift s of each 40Ca+ single-ion optical clock were carried out in WIPM. A Ti:sapphire laser at 729 nm is frequency stabilized to an ultra-stable ultra-low thermal expansion coefcient (ULE) cavity by means of Pound-Drever-Hall method. 1 Hz linewidth and 2×10−15 frequency stability at 1-100 s is realized. Which is used for the probe of 40Ca+ optical transition. Aft er compensating for the micromotion, the two optical clocks both reach an uncertainty level of a few parts in 10−17. Th e dominant source of uncertainty is the blackbody radiation (BBR) shift aft er minimizing the micromotion-induced shift s. Th e BBR shift is evaluated by controlling and measuring the temperature at the trap center. With a measurement over one month, the frequency diff erence between the two clocks is measured to be 3.2 (5.5)×10−17. Due to improvement of the clock laser and better control of the optical and electromagnetic feld geometry and the laboratory conditions, a fractional stability of 7×10−17 in 20,000 s of averaging time is achieved. Th e absolute frequency of the 40Ca+ 4s 2S1/2- 3d 2D5/2 clock transition is measured to be 411 042 129 776 401.7 (1.1) Hz, with a fractional uncertainty of 2.7 × 10−15 using the GPS satellites as a link to the SI second.

Biography:

Konsantin Lyakhov has completed his PhD from Frankfurt University. He is working as a Research Professor in Nuclear and Energy Engineering Department of Jeju National University. He has published 12 papers in SCOPUS indexed journals.

Abstract:

Laser pulse shape manipulation can serve as an effi cient tool for selective quantum level population control. In this paper it will be demonstrated parametrization of laser pulse shape, parameters variation of which can be implemented by an optical mask applied to the seed pulse. Its further amplifi cation is provided by subsequent cell fi lled by CO2 laser medium, the output laser pulse is subject to use in the method of isotopes separation by selective retardation of condensation in overcooled gas fl ow(SILARC), for selective excitation of all four chlorine isotopologues of 11BCl3 with small time delays, corresponding to respective levels population build up times. It is acheieved by that laser pulse emission spectrum has modes matching absorption lines of diff erent chlorine isotopologues in 11BCl3. In order to provide the largest interaction volume of gas fl ow with laser beam, the latter should intersect it as many times as possible and ambient gas pressure should be maintained on the level, such that gas fl ow remains planar over all its extension from the nozzle outlet to the skimmer inlet. In order to save expensive laser photons, we assume, that refl ectivity of mirror walls is very high and resonator condition inside irradiation cell is fulfi lled. Comparison of our results for enrichment factor and product cut time evolution with one mode continuous excitation indicates that pulsed irradiation with specifi cally designed laser pulse shape allows to increase extractable per cycle isotope quantity signifi cantly at the same energy expenses. Calculations were carried out at the temperature and initial laser intensity, corresponding to the maximum of isotope production over gas fl ow transition time across irradiation cell. Gas fl ow static pressure and BCl3 molar fraction in carrier gas-argon are chosen to fi xed at some small values minimize isotope scrambling.

Biography:

Yanbo Bai has completed his PhD from Northwestern University. His research led to develop the most effi cient and most powerful quantum cascade lasers. His current role at Coherent is to develop more effi cient optically pumped semiconductor lasers and explore new wavelength capabilities. He has published more than 40 papers in reputed journals, such as Nature Photonics, Applied Physics Letters, Journal of Applied Physics, etc.

Abstract:

Self-heating of optically pumped semiconductor (OPS) chip has been identifi ed as the major limiting factor of power scaling in OPS-based lasers in continuous wave (cw) mode. In this work, characterization of OPS lasers in short pulse (100 ns) and low duty cycle (1%) regime, where self-heating is negligible, as a function of the heat sink temperature is presented. The is data, combined with a rigorous thermal model, allows us to predict OPS chip performance in new cooling confi gurations for power scaling. Furthermore, the temperature dependent pulsed mode measurement data can be used to calibrate a temperature dependent gain model based on the 8-band kp method, taking the Auger coeffi cient as the fi tting parameter, thus allowing for predicting the performance of new structures. Th e pulsed-mode testing proved to be a valuable technique to reveal the OPS chip quality independent of the thermal management and to validate the OPS gain model.

Biography:

Simone Borri has completed his PhD in 2007 from University of Firenze, Italy. He is Researcher at CNR-National Institute of Optics since 2010. His main expertise is development of coherent sources and techniques for high-sensitivity and high-resolution molecular spectroscopy in the mid infrared. During his scientifi c activity he developed mid-IR and THz sources based on nonlinear frequency generation and worked on trace-gas sensors based on cavity-enhanced absorption spectroscopy, photoacoustic sensing, Doppler-free spectroscopy. He studied the noise properties of quantum cascade lasers and developed locking techniques for linewidth narrowing. He is author of more than 30 publications in peer-reviewed journals.

Abstract:

Molecular precision spectroscopy opens new perspectives on tests of fundamental laws of physics and fundamental constants variation. The mid infrared (IR) is a key region for molecular spectroscopy and the eff orts towards the development of versatile, spectrally pure and tunable coherent sources in this region have been constantly growing in the last decade. During the last years, we have made signifi cant eff orts in the development of metrological-grade coherent sources. Here, we present our more recent work based on two diff erent approaches, both involving frequency-stabilized mid-IR quantum cascade lasers (QCLs). The first approach is based on crystalline fl uoride whispering-gallery-mode resonators. Th ese devices have started to show their full potential for mid-IR photonics in the last two years. Th ey demonstrated record Q-factors (~108 around 4.5 μm) and a further increase is expected with the improvement of materials and fabrication techniques. We successfully tested a compact apparatus for high-precision spectroscopy based on mid-IR QCLs locked to fl uoride resonators. The  low sensitivity of the resonator to environmental noise is one of the strengths of this approach, leading to good stability levels even over long timescales (10 kHz on 1s timescale). The second approach is based on the combination of a mid-IR QCL and a metrological-grade source based on diff erence frequency generation using an OP-GaP crystal. Here we take advantage of the optical reference delivered from the Italian national laboratory for metrological research (INRIM) through a stable and ever-growing fi bre network. The is combination allows for mW-level radiation that covers, in principle, the entire molecular fi ngerprint region, with linewidths at kHz level and with a phase-noise compatible with a 10−14 shortterm instability.

Biography:

Ramesh G Mani obtained his PhD in Physics from the University of Maryland–College Park. He has worked at the Max-Planck-Institute for Solid State Physics in Stuttgart, Germany, University of California–Santa Barbara and Harvard University. He is presently a Faculty Member at Georgia State University in Atlanta, GA. He invented the “anti-hall bar” geometry and demonstrated dual/multiple simultaneous ordinary and quantized hall effects in a single specimen. The work served as the basis for many international patents relating to offset voltage reduction in hall sensors. He also discovered the microwave radiation-induced zero-resistance states in the two dimensional electron system.

Abstract:

The Hall-eff ect remains broadly important nearly 140 years aft er its discovery. In science, the integral and fractional- quantum Hall eff ects have revolutionized condensed matter physics. Meanwhile, the classical Hall-eff ect remains a vital semiconductor characterization tool and proven contactless-sensing technology for essential applications. Recent work, see C. Kern et al., Phys. Rev. Lett. 118, 016601 (2017), claims novel sign reversal of the Hall-coeffi cient in chain-mail-like 3D metamaterials, whereby an n-type semiconductor mimics the Hall-eff ect of a p-type semiconductor, see also Physics Today 70 (2), 21 (2017); Nature 544, 44 (2017). Measurement-geometry-related Hall-eff ect sign-inversion is known from studies of 2D or 3D- semiconductor plates including a hole with current and voltage contacts placed on the interior boundary of the hole (see R. G. Mani et al., Appl. Phys. Lett. 64, 1262 (1994); Z. Phys. B 92, 335 (1993); Patents: DE 4308375C2; U.S. 5,646,527; EP 0689723B1). Studies of such “anti-hall bars” demonstrate a
sign reversed Hall-eff ect with respect to the standard hole-less geometry. A Hall-bar including a single supplementary hole can be transformed into an “anti-hall-bar” by turning the sample inside out, which shift s the exterior boundary and contacts to the sample interior while moving the hole-boundary to the exterior. For a fi xed direction of the magnetic fi eld B, device-inversion leads to signreversal of the Hall-eff ect in “anti-hall bars” since the device-orientation becomes fl ipped with respect to B. Here, we discuss the relation between such sign inversion and the reported sign reversal of the Hall coeffi cient in metamaterials.

Biography:

Yohei Sato has received a Master’s degree in Material Sciences from Tohoku University in March 2017. He joined Oyama Laboratory in Sendai, Japan in 2015. Since then, he has been engaged in research of solution growth of semiconductor and THz wave generation from the grown semiconductor crystal.

Abstract:

The applications of THz wave are expected in wide valiety of applications such as nondestructive inspection, medical science and ultra high density communication. In our laboratory, we research nondestructive inspection by using THz wave as follows: 1. Sensing of disconnection gaps covered with invisible insulator, 2. visualization of steel wire in the extradosed bridge cable and 3. qualitative and quantitative metal corrosion analysis etc. For these THz killer applications, non-linear optical gallium selenide (GaSe) is one of the most essential key materials for the highly effi cient, widely frequency tunable and compact THz light source via diff erence frequency generation. Th e power of THz wave from commercially available Bridgman grown GaSe crystal is limited by the native point defects due to high temperature growth at melting point and the deviation from stoichiometric composition. In our laboratory, GaSe crystal is grown by TDM-CVP which enables extremely low growth temperature and application of Se vapor pressure for stoichiometry control. Conversion effi ciency of THz wave generation at 9.41 THz using not-intentionally doped GaSe crystal grown by our TDM-CVP (1.2×10-6 J-1) was 4 times higher than that from Bridgman-grown crystal (3.0×10-7 J-1). In addition, we grew impurity doped GaSe crystal systematically for the fi rst time. In low THz frequency range, transparency of GaSe crystals grown by TDM-CVP are improved by doping of amphoteric impurity (Ge) and transition metal (Ti). In the case of doping issoerectronic impurity (Te), It was confi rmed to improve interlayer bonding force of GaSe crystal by doping of Te.

Biography:

Qi Jie Wang received his PhD degree in Electrical and Electronic Engineering from Nanyang Technological University, Singapore in 2005. After completing his PhD, he joined the School of Engineering and Applied Science, Harvard University, as a Post-doctoral Researcher. In October 2009, he was assigned as a Joint Nanyang Assistant Professor at the School of Electrical and Electronic Engineering (EEE) and the School of Physical and Mathematical Sciences (SPMS). Since Feb 2015, he has been promoted to tenured Associate Professor in School of EEE and SPMS, NTU.

Abstract:

Currently, terahertz (THz) optical systems are based on bulky free-space optics. This is due to the lack of a common platform onto which diff erent THz components, e.g., source, waveguide, modulator and detector can be monolithically integrated. With the development of THz quantum cascade laser (QCL), it has been realized that the QCL chip may be such a platform for integrated THz photonics. Here, we report our recent works where the THz QCL is integrated with passive or optoelectronic components. They are: 1) integrated graphene modulator with THz QCL achieving 100% modulation depth and fast speed; 2) phase-locked THz QCL with integrated plasmonic waveguide and subwavelength antennas realizing dynamically widely tunable polarizations.

Biography:

Cunzhu Tong is working as a Professor at the Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP), Chinese Academy of Sciences (CAS). He received his PhD degree from CAS in 2005 and became the Professor of Hundred Talent Programs of CAS in 2010. He was the Distinguished Elite Professor of CAS and the Standing Committee Member of Chinese Society Astronautics. He has won several awards including the Outstanding Young Scientist Award of Scientifi c Chinese, the Excellent Award for Hundred Talents Program and the Important Achievements in China Optics in 2015. He has authored and co-authored over 80 refereed journal papers.

Abstract:

High power diode lasers are the key elements in a wide range of applications such as pumping for solid-state lasers and fi ber lasers, data transfer and material processing and the devices with high emission power and low far-fi eld divergence are desired for many applications. Bragg refl ection waveguide lasers and longitudinal photonic bandgap crystal (LPBC) lasers have been proposed to realize the high brightness diode lasers based on the PBC mechanism. In these devices, light is confi ned by the photonic band-gap eff ect in vertical direction rather than by total interface refl ection (TIR) and low vertical divergence and circular beams have been demonstrated in single devices. In this paper, we introduce our recent work on the high brightness diode lasers based on the PBC waveguide with lateral microstructure. Th e one dimensional PBC structure demonstrated the low divergence (<50) in fast-axis, the lateral microstructure showed the evident improvement of beam quality in slow-axis. Th e high effi ciency of directly coupled into fi ber was achieved. Th e high-power PBC lasers were used for external-cavity spectral beam combining (SBC) and the high brightness was demonstrated.

Biography:

Nasser Peyghambarian is a Professor at the College of Optical Sciences and the Department of Materials Science and Engineering at the University of Arizona (UA), as well as the Director of the NSF Engineering Research Center for Integrated Access Networks and the UA Chair of Photonics and Lasers. He is a Fellow of the AAAS, OSA, SPIE, APS and NAI. He has over 600 publications in peer-reviewed journals and more than 700 invited talks, conference proceedings and presentations. He has authored or co-authored 28 books and book chapters and is the inventor on 38 patents.

Abstract:

Phosphate, telluride and fl uoride glasses allow new fi ber laser frequencies. Nonlinear eff ects including Second Harmonic Generation (SHG), Optical Parametric Oscillators (OPO), Stimulated Raman Scattering (SRS) and Stimulated Brillouin Scattering (SBS) extend the operating wavelengths. However, some nonlinear eff ects including SRS in some cases are not desirable as they prevent high power operation. Our recent advances include: Demonstration of blue laser using Tm-doped fl uoride glass; Demonstration of midinfrared (mid-IR) frequency comb spanning from 7.5-11.6 μm using diff erence frequency generation (DFG) in a AgGaS2 crystal with a compact all-fi ber source based on Tm and Er-amplifi ers. Th e power of the mid-IR signal is measured to be 1.55mW and the photon conversion effi ciency is 15%. Th e pulse duration achieved in the mid-IR range is estimated to be around 80fs, which corresponds to 2.6 optical cycles at 9.2 μm center wavelength. Th e current approach allows simple power scaling by further amplifi cation of the pump and signal pulses using established amplifi er technologies. Demonstration of Er3+-doped ZBLAN fi ber amplifi er for Q-switched pulses at 2.79 μm is reported. Over 24 μJ pulse energy at an average output power of 1.0 W was achieved at a pump power of 9.4 W. The effi ciency of this pulsed laser fi ber amplifi er is about 10%. Our simulation predicts that over 250 μJ pulses can be achieved with this fi ber amplifi er when a 120 W pump is used. Demonstration of mid-IR supercontinuum sources will also be discussed.

Biography:

Robert L Green has earned his BS from Morehouse College, an MS from Purdue University and his PhD from the University of South Carolina in Chemistry. For the majority of his 12 years career in higher education, he has devoted time to promoting STEM education to both K-12 teachers and students underserved communities. He is a Member of the American Chemical Society and is the Founder of the Florida Polytechnic University Chapter of the National Society of Black Engineers (NSBE).

Abstract:

A high-resolution neutron powder diff raction technique was used to observe and refi ne the structural details of the ordered hexagonal oxyfl uoride Na2CaVO4F. Polycrystalline samples were prepared via solid-state synthesis using stoichiometric amounts of high pure starting materials. Th e structural changes between 25°C and 750°C revealed that the two structural subunits contained within this material exhibit diff erent behavior when heated. Th ere is an expansion of the face-shared FNa4Ca2 octahedra while the VO4 tetrahedra due to increased thermal disorder reveal marginal bond contractions. Th e bond valence method is employed to compare observed and ideal bond distances and point to a structural instability at 750oC. Th e Echidna high-resolution powder diff ractometer located at the OPAL Research Reactor of the Australian Nuclear Science and Technology Organization (ANSTO) was used for both room temperature and temperature-dependent studies whereby diff raction data was collected using a neutron beam with a wavelength of 1.6215(1) Å using a Ge (335) monochromator. All preliminary structural information was collected using a benchtop X-ray diff ractometer using Cu-Kα (1.54059 Å) over the range of 3-149° 2-theta. Both X-ray and neutron diff raction data was refi ned using the GSAS suite of programs.

Biography:

Yutaka Fukuchi received his BS and MS degrees in Electronics Engineering from Tokyo University of Science, Japan in 1998 and 2000, respectively and completed his PhD degree in Electronics Engineering from University of Tokyo, Japan in 2003. In 2003, he joined the Department of Electrical Engineering, Tokyo University of Science. Since 2009, he has been an Associate Professor in this department. From 2013 to 2014, he was a Visiting Research Fellow with the Department of Photonics Engineering, Technical University of Denmark. His research interests are nonlinear optics and their applications.

Abstract:

Optical frequency comb generators can off er several attractive applications such as wideband multi-wavelength lasers, ultra-short pulse generation, coherent optical waveform syntheses, ultra-fast signal processing, high resolution spectroscopy and optical frequency reference. High stability, high coherence, high effi ciency, low noise, low cost, wide bandwidth and spectral fl atness are commonly required for those applications. Among many potential comb sources, harmonically mode-locked fi ber lasers are a popular solution owing to their abilities such as wavelength tunability, short pulse width, small timing jitter and high repetition frequency in the gigahertz region. However, since the harmonically mode-locked fi ber lasers usually employ silica-based erbium-doped fi bers as the gain media, the range of the wavelength tunability is limited to either the conventional wavelength band or the longer wavelength band. Furthermore, it is generally diffi cult for each frequency comb component generated by the harmonically mode-locked fiber lasers to have the same intensity. In this paper, we review a technique for producing a tunable and fl at frequency comb from a 10 GHz bismuth-based harmonically mode-locked fi ber laser. Th e output characteristics are as follows. Th e center wavelength can be tuned from 1535 nm to 1585 nm. Th e comb spectrum can be fl atly broadened up to 2.4 nm (300 GHz) with 30 comb lines. Th e spectral width and the pulse width can be tuned from 0.23 nm to 2.4 nm and from 3.0 ps to 20.1 ps, respectively. Th roughout the entire tuning ranges, this laser can maintain stable bit-error-free mode-locking operation within a received power deviation of 3.0 dB.

Biography:

Taiji Sakamoto received his BE, ME and PhD degrees in Electrical Engineering from Osaka Prefecture University, Osaka, Japan in 2004, 2006 and 2012 respectively. In 2006, he joined NTT Access Network Service Systems Laboratories, NTT, Ibaraki, Japan where he has been engaged in research on optical fi ber nonlinear effects, low nonlinear optical fi ber, few-mode fi ber and multi-core fi ber for optical MIMO transmission systems. He is a Member of the Institute of Electronics, Information and Communication Engineers.

Abstract:

The capacity of conventional single-mode fi ber (SMF) that is widely used in the existing optical communication network is expected to be limited to around 100 Tbit/s owing to the non-linear eff ect of the optical fi ber. Space division multiplexing technologies using multi-core fi ber (MCF) or few-mode fi ber have been investigated for overcoming the capacity crunch of conventional SMF. MCF has multiple cores within a cladding and multiple signals can be transmitted in parallel by using multiple cores. One important parameter for MCF is spatial density, namely the number of spatial channels per unit area, since the cladding diameter of the fiber is limited to a certain value in terms of mechanical reliability. Recently, coupled MCF which has a low core pitch value between the cores compared to the non-coupled MCF has been investigated with the aim of improving the spatial density. In this paper, we review recent progress on coupled multi-core fi ber (MCF) technologies and advantages of using this type of MCF for optical MIMO transmission system. Finally we report our recent results for high spatial density randomly-coupled MCF with low modal dispersion characteristic, which is benefi cial for realizing long-haul optical MIMO transmission.

Biography:

Jiaren Liu has completed his PhD in 1993 from Nanjing University of Science and Technology and then completed his Post-doctoral studies from Texas A&M University and University of Toronto. He is a Senior Research Offi cer of National Research Council of Canada and an Adjunct Professor of Concordia University. He has published 50 more papers in reputed journals and other 70 more papers in conferences and seminars.

Abstract:

Phase noise or linewidth of semiconductor diode lasers is vital parameter for various applications in optical sensing and coherent communication. In this talk, phase noise of individual mode in InAs quantum-dot (QD) mode-locked lasers (MLLs) made by National Research Council of Canada were investigated both theoretically and experimentally. Under optimized mode-locked conditions, the minimum linewidth of individual modes is about 0.6MHz, 0.8MHz, or 0.9MHz achieved for the repetition rate of 11GHz, 25GHz, or 34GHz respectively. For MLLs with the above channel spacing, the linewidths of 10 or more laser modes can go down to 1.0MHz at least. Th e relevant experimental result is consistent and fi tted with the theoretical prediction which assumes zeromean Gaussian random processes for both common mode and un-common mode phase noises. Such low phase noise MLLs will be the suitable and cost-eff ective candidate for multiple wavelength applications in long-haul and data-center fi ber optical networks.

Biography:

Sang-Rok Moon has received his BS degree in Physics in 2008 and his PhD degree in Electrical Engineering in 2015 from Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea. He is working at Electronics and Telecommunications Research Institute (ETRI) from 2015. His current research interest includes, orthogonal frequency-division multiplexing (OFDM) and optical cummunisation in metropolitan/access network.

Abstract:

We investigate feasibility of carrier frequency off set (CFO) compensation method using optical feedback path for coherent optical orthogonal frequency division multiplexing (CO-OFDM) system. CFO compensation is one of most important issues in OFDM system, since the CFO breakes orthogonality among OFDM subrarriers and it causes critical degradation in signal quality. In CO-OFDM, the CFO tends to be high because of laser instability. Th us wide CFO compensation range is essential. Recently proposed CFO compensation algorithms provide wide CFO estimation range. Th ey compensate CFO aft er anlog-to-digital convertor (ADC). Then, CFO compensation range is limited by sampling rate of the ADC. Th us, the sampling rate should be much higher than
CFO and/or data bandwidth. Because of high price of ADC, it is not aff ordable in practical CO-OFDM. To solve this problem, we propose a CFO compensation method having optical feedback path. Th e measured CFO is used to control local oscillator’s wavelength for CFO compensation. Since the CFO is compensated before ADC, the compensation range is not aff ected by the ADC. Residual CFO can be compensated by conventional CFO compensation methods. Th e feasibility of the proposed method is experimentally investigated. We showed that the practical CFO compensation range can be extended to the sampling frequency range, regardless of sampling rate of ADC. Although the proposed method is based on OFDM, the proposed method works in all coherent modulation formats with minor modifi cation.

Biography:

Jair Adriano Lima Silva received his BS, MS and PhD degrees in Electrical Engineering from the Federal University of Esp´ rito Santo (UFES), Vitória, Brazil in 2003, 2006 and 2011 respectively. In 2012, he joined the Department of Electrical Engineering of UFES. His research interest include optical fi ber communication, radio-over-fi ber, orthogonal frequency division multiplexing, passive optical communication network, visible light and powerline communiactions.

Abstract:

The resilience towards fi ber dispersion is the main attractive feature of orthogonal frequency division multiplexing (OFDM) signal processing in optical communications systems. Coherent-detection optical OFDM (CO-OFDM) posses many benefi ts that are critical for high data rate fi ber transmission systems. It is extremely robust against chromatic and polarization mode dispersions at the same time that it improves spectral effi ciency eliminating the need for a guard band between the optical carrier and the informationbearing signal. Furthermore, adaptive data rates with diff erent subcarrier mapping levels can be supported using soft ware-defi ned solutions. However, large peak-to-average power ratio (PAPR) of the inherent multicarrier signals is one of the main drawbacks in CO-OFDM systems, as it not only limits the resolution of digital-to-analog converters and power amplifi ers, but also reduces the tolerance to the nonlinearities introduced by Mach-Zehnder (MZM) optical modulators and optical fi bers. Several PAPR reduction techniques such as coding, tone reservation, clipping, peak windowing and partial transmit sequence, have been proposed in the literature. Th ese distinctly techniques provide diff erent degrees of eff ectiveness and tradeoff s that may include increased complexity, reduced spectral effi ciency and performance degradation. Recently, we proposed a PAPR reduction scheme based on constant envelope (CE) signals to improve the tolerance towards MZM modulators and fi ber nonlinearities in direct-detection optical OFDM systems. As a power effi cient technique, it reduced the PAPR to 3 dB using electrical phase modulation (PM). Aft er a successful experimental demonstration in direct-detection optical systems, this CE-OFDM technique was introduced in coherent detection systems as a suitable solution to the aforementioned problems. Unlike the approaches evaluated in the literature, the intermediate electrical constant-envelope signals of this solution were used to modulate the continuous wave laser source, employing a conventional one-branch MZM modulator. Th e infl uence of the electrical phase modulation index h in the performance of CE-OFDM in coherent detection optical systems was treated analytically and its range of validity examined by simulations. A compromise between h and subcarrier mapping was identifi ed according to diff erences in sensitivity related to non-linearities inserted by the MZM. We showed that the proposed scheme outperforms conventional coherent detection OFDM systems.

Biography:

Reginaldo Barbosa Nunes has completed his PhD degree in Electrical Engineering from Federal University of Espírito Santo (2016), graduated in Electrical Engineering, Master’s in Computer Science and Computer Network Specialist. He is working as a Professor of higher and technical education at the Federal Institute of Espírito Santo from 1997. He has recently published more than 15 papers in reputed journals and international conferences, has been serving as reviewer member in several international periodics.

Abstract:

The need for high bandwidth networks driven by new digital services and technologies has culminated in the emergence of the new standards for passive optical networks (PONs) such as 10 Gigabit Capable PON (XGPON) recommended by the ITU-T (International Telecommunications Union - Telecommunications) and 10 Gigabit Ethernet PON (10G EPON) standardized by the IEEE (Institute of Electrical and Electronic Engineers), both provide rates up to 10 Gb/s per wavelength to the end user. More recently, the ITUT standard NGPON2 started using TWDM technology that provides rates up to 40 Gb/s, but for that, it needs to use four wavelengths. In this context, this we propose a PON architecture based on Orthogonal Frequency Division Multiple Access (OFDMA), capable to off er an effi cient bandwidth control with greater fl exibility and granularity in bandwidth allocation to the end users according their demand or required Quality of Service (QoS). Th e proposed architecture exploits the Orthogonal Frequency Division Multiplexing (OFDM) to provide transmission rates above 33 Gb/s per wavelength. Th e proposal considers a tree topology where each optical line terminal (OLT) is connected to at least one passive device splitter/combiner, provides multiple services for up to 32 optical network units (ONUs). Our work presents experimental results that demonstrate the feasibility of this physical infrastructure for passive optical network based on OFDM/OFDMA, suggests adaptations in the architecture and presents techniques for improving the system spectral effi ciency. In addition, it also describes the main recommendations to build a medium access layer in accordance with this proposal, named BS OFDMA PON (Bandwidth Scalable OFDMA PON).

Biography:

Jianjun Yu has completed his PhD in the year of 1996 from Beijing Univeristy of Posts and Telecommunications. He is the Professor of Fudan University. He has published more than 600 papers in reputed journals and has been serving as an Editorial Board Member of IEEE Photonics Journal, JLT and JOCN.

Abstract:

With the popularization of data centre and other bandwidth hungry inter-connect applications, the desired capacity of short reach optical network has exponentially increased to 400 Gbit/s or even more. Recent standardization eff orts for 400 G intradata center connections specify link lengths of up to 2 km. 8×56 Gb/s or 4x100 Gb/s could enable such 400 G networks. Relative to coherent detection. Intensity modulation/direct detection (IM/DD) is a good candidate in inter-connect due to its low cost. For 56 and up to 100 Gb/s signal generation, a few modulation formats or schemes, such as pulse-amplitude-modulation (PAM4), discrete multitone (DMT), duobinary and chirp-managed laser (CML) are proposed and experimentally demonstrated. However, considering cost, size and power comsuption, the modulation format should be optimized for diff erent networks to meet diff erent requirements. In this talk, we will discuss this issue how to optimize the modulation formats for diff erent optical networks?

Biography:

Dongsun Seo has received his PhD degree in Electrical Engineering (Optoelectronics) from the University of New Mexico in 1989. In 1990, he has joined the Faculty of Myongji University, Korea, where he is currently a Professor in the Department of Electronics. From 2002 to 2004, he was with Purdue University, as a Visiting Research Professor in the School of Electrical and Computer Engineering. He has published over 70 journal articles and over 100 conference papers. His current research interests are in the areas of optical pulse sources, ultrafast optics, high-capacity optical communications, optical processing and photonics.

Abstract:

In this talk, we discuss novel schemes that improve signifi cantly the spectral effi ciency (i.e., channel capacity) of an optical access link. Firstly, an optical orthogonal frequency division multiplexing (OFDM) signal, which is encoded by multilevel quadrature amplitude modulation (QAM), is compressed using the proposed sampling scheme sampled at a lower than conventional Nyquist rate. At the receiver, the OFDM signal is recovered by a Bayesian compressive sensing (CS) technique. We show experimentally the spectral effi ciency improvement (i.e., data compression) up to <40% and <20% for 4-QAM and 16-QAM encoded OFDM waveforms, respectively. Secondly, we discuss channel capacity improvement by simultaneous modulation of amplitude, phase and frequency i.e., by combining frequency shift keying (FSK) and QAM. Th is 3-dimensional modulation so called NOFQAM, increases the modulation order dramatically by multiplying both the FSK and QAM orders. Unlike a conventional orthogonal FSK modulation, the FSK channels are overlapped in our non-orthogonal (NO) FSK modulation. Th erefore, the NO-FSK modulation increases the channel capacity at a fi xed channel bandwidth. For experimental verifi cation, we implement a 20-km optical access link, which transmits a 64-NOFQAM signal formed by combining both 4-FSK and 16-QAM. Th e symbol rate and FSK channel spacing are 200 M-symbol/s and 45 MHz, respectively. Comparing to a 200 M-symbol/s 16-QAM transmission, the suggested 64-NOFQAM transmission shows negligible increase in the occupied channel bandwidth and very small power penalty less than 0.5 dB. Finally, we apply the CS based data compression technique to the 64-NOFQAM signal and show greater than 50% of data compression.

Biography:

Jesse A Frantz has received his PhD in Optical Sciences in 2004 from the Optical Sciences Center at The University of Arizona. He has been working as a Research Physicist at NRL since 2004 where his research is focused on microstructured optical surfaces and novel thin fi lm materials. He established and manages a Vacuum Deposition Cluster System Facility in NRL’s Optical Sciences Division used for a variety of projects including the fabrication of advanced, multi-layer thin fi lm devices for optical applications.

Abstract:

Anti-refl ection surface structures (ARSS) are nano-scale features patterned directly into an optical surface that are designed to have low optical refl ectance. Th ey have been demonstrated to increase the transmission of an optical surface to >99.9% and are an attractive alternative to traditional thin fi lm anti refl ection (AR) coatings for several reasons. They provide AR performance over a larger spectral and angular range and unlike thin fi lm AR coatings, they are patterned directly into the optic rather than deposited on its surface. As a result, they are not prone to delamination under thermal cycling that can occur with thin fi lm coatings and their laser damage thresholds can be considerably higher. In this presentation, we summarize results for ARSS on a variety of optical materials including silica, germanium, magnesium aluminate spinel and a variety of laser crystals. We discuss scale-up of the technique and describe results for ARSS with dimensions as large as 33 cm. We describe a surface modifi cation procedure that results in a superhydrophobic surface without a signifi cant decrease in transmittance. Finally, we show results for optical performance of ARSS on silica windows following sand and rain erosion testing showing that they are suitable for use in harsh environments.

Biography:

Eugene S Smotkin has completed his PhD from University of Texas at Austin. He is the Professor of Chemistry Northeastern University and CEO of NuVant Systems Inc., a premier electrochemical technology organization. He has published more than 80 papers in reputed journals and has 15 patents.

Abstract:

Steady state operando confocal Raman microspectroscopy of polymer electrolyte membrane fuel cell catalytic layers is challenged by thermal damage to the catalytic layer resulting from excessive luminescence within a focal point sampling region. Experimentalists must exclude catalyst material along the optical axis path or position the axis between (parallel) the catalytic layers. We demonstrated that operando non-confocal Raman microspectroscopy of a catalytic layer yields high quality spectra elucidating changes in the membrane ion exchange site local symmetry as the fuel cell transitions from open circuit to oxygen reduction potentials. We now explain how non-confocal microscopy enables steady state layer-by-layer spectroscopic profi ling with no thermal damage to “black” layers?

Biography:

Takahiro Tsukahara has completed his PhD in the year 2007 from Tokyo University of Science. He is an Associate Professor of Department of Mechanical Engineering, Faculty of Science and Technology, Tokyo University of Science. He has published more than 37 papers in journal publications and 44 peer-reviewed proceeding papers. He has been serving as an Editorial Board Member of Advances in Mechanical Engineering. He has his expertise in Thermo-fl uid Dynamics, especially in Turbulent Transition and Flow Instability, and Computational Fluid Dynamics.

Abstract:

Non-invasive and non-contact manipulation of micro-scale droplet in air/liquid pool, which is relevant to Medical or Biological Engineering applications and chemical processes using lab-on-chip technology, has increasingly attracted attention in the fi eld of microfl uidics. Several techniques were proposed by utilizing a local variation of interfacial tension, because the eff ects of interfacial phenomena are dominant in microfl uidics relative to the inertia and buoyancy forces. In particular, laser-induced optical force may be used as a non-invasive and precise tool for droplet-based controls, but its force magnitude is limited on the order of a pico newton. Compared to the optical force, an optically-induced thermal Marangoni convection may provide a larger resultant force that provides the nano-newton order force. Th erefore, the photothermal Marangoni convection can be a powerful technique of on-demand bubble/ droplet handling in a micro-channel liquid. If allowed to change physical properties of surfactant solution liquid (e.g., azobenzene) in response to light, the cis-trans photoisomerization can be alternative non-invasive fl uid manipulation without adding heat. The cis-trans photoisomerization is a property that the cis and trans isomers are reversibly changed by light of a specifi c wavelength such as ultraviolet light. As the isomers of diff erent molecular structures are switched by light irradiation, physical properties such as the contact angle and interfacial tension are varied. We have performed direct numerical simulation of multi-phase fl ows of droplets that are accompanied by either photo-induced thermal Marangoni convection or cis-trans photoisomerization, in order to study quantitatively the force and mechanisms relevant to the laser-based droplet manipulation.

Biography:

Robert Claude Gauthier has completed his PhD in 1988 from Dalhousie University (Halifax, Canada). He is presently associated with the Department of Electronics at Carleton University, (Ottawa, Canada). He has published numerous papers primarily in the areas of optical fi ber sensors, optical levitation and trapping, photonic crystal and photonic quasicrys. His research interest now focus on numerical studies of optical resonator properties

Abstract:

Numerical simulations of electromagnetic phenomena provide the researcher and the component designer with a cost eff ective alternative to device manufacturing of prototypes. Techiques such as FDTD and FEM are commonly employed but hit up against speed and memory boundaries when structures are irregular or extend over all three coordinate axis. Th e talk will present a numerical technique, based on spectral analysis, which is suitable for numerical analysis of structures which present cylindrical and spherical geometries. Th e theoretical foundations of the numerical technique will be presented which takes its roots in Maxwell’s curl coupled equations rather than the usual wave equations. Th e eigenvalue matrix system properties were explored and symmetry techniques utilized to reduce the matrix order and tune “mode family” computations were highlighted leading to faster computation engines. Several computation examples will be presented indicating the suitability of the technique to obtain localized states in resonators, axially propagated fi elds in fi ber geometries and in spherical resonators. Recently, the numerical process has been inverted such that the material properties of an optical resonator and waveguide can be determined based on the user defi ned modal profi le and propagation properties selected by the designer theoretical details and numerical examples of the inverse process will close the presentation.

Biography:

Holger Kreilkamp is Group Manager of “Optics” at Fraunhofer Institute for Production Technology IPT. He studied Mechanical Engineering specialized in Production Technology at RWTH Aachen University and received his Diploma degree in 2011. He got a second Diploma in Economics in 2012. Since then, he has worked as a Research Assistant at Fraunhofer IPT in the fi eld of Optics Manufacturing. His research focuses on technology development for glass optics production with special interests in replicative manufacturing.

Abstract:

Digitalization, adaptivity and networked production are dominant issues for state of the art manufacturing technologies and will continue to have a substantial impact on their advancement and development. Th is applies especially to complex process chains, characterized by multiple and non-trivial interdependencies, such as the replicative manufacturing of optical components. Ranging from the optical design, the FEM simulation and the mold manufacturing, down to the actual molding process and the assembly of the optical system, this process chain today reveals a low level of automation as well as insuffi cient (data-)standards and an inadequate information fl ow over the diff erent process steps. Since most of the single technologies are at the brink of technical feasibility, future components will need the ability to exploit the vast potential of interconnected and adaptive process chains. In order to promote and advance this transition in the fi eld of replicative optics manufacturing the Fraunhofer IPT has elaborated an innovative and comprehensive data solution concept, which has been implemented within the precision glass molding process (PGM). In a specially equipped glass molding machine, tailored sensor systems are collecting multiple data concerning the molding process, such as temperature, force and pressure profi les. Th is information is acquired in real time and serves the purpose of immediate visualization. Beyond this, all data are fed into a superior data backbone, allowing the reconstruction of an exact digital image of the component, highly valuable to adapt downstream and upstream processes, granting a glance on what future optics production in a totally digitalized production environment will look like.

Biography:

Baptiste MOT has completed his MSD in the year 2004 from the “conservatoire national des arts et métiers”. He works as a Research Engineer in an Astrophysic laboratory on several space telescopes.

Abstract:

PILOT is a balloon-borne astronomy experiment designed to study the polarization of dust emission in the diff use interstellar medium in our Galaxy at wavelengths 240 μm and 550 μm with an angular resolution of a few arc-minute. PILOT optics is composed an off -axis Gregorian type telescope and a refractive re-imager system. All optical elements, except the primary mirror, are in a cryostat cooled to 3K. We combined the optical, 3D dimensional measurement methods and thermoeslastic modeling to perform the optical alignment. I will present the system analysis, the alignment procedure, and fi nally the performances obtained during the second fl ight in March 2017.

Biography:

T K Subramaniam has completed his PhD from Banaras Hindu University, India, specializing in Laser Spectroscopy. He is presently working as Professor of Physics at Sri Sairam Engineeering College, Chennai, India, teaching Under-graduate Physics at the college level for more than 20 years and also has six years of industrial experience. He has published more than 10 research papers in international journals of repute and is a Peer-Reviewer for the Optical Society of America (OSA) group of journals, besides serving in the Editorial Board of other reputed journals. Recently, he has presented a research paper at Olching, Germany, in November 2016.

Abstract:

Rain bearing clouds can be eff ectively guided to a specifi c region during monsoon or other seasons so that rainfall shall be equitably distributed without creating drought situations. Lasers sent into the lower troposphere region with power in Gigawatt ranges, suffi cient to create a temperature and pressure gradient and thereby creating a low pressure area in a specifi c region can invite rain bearing clouds in a region opposite to the heat and pressure gradient created by laser eff ects, so as to bring convective rainfall during a season. Pressure gradient describes the diff erence in air pressure between two points in the atmosphere or on the surface of the Earth. It is vital to wind speed, because the greater the diff erence in pressure, the faster the wind fl ows (from the high to low pressure) to balance out the variation. Satellite based monitoring system of cloud formations can be an eff ective guide to send laser beams in a direction towards the lower troposphere to create convective rainfall into another specifi c region.Laser beams are an attracted means of carrying concentrated power over distance. Hence, we choose a CO2 laser (λ=10.6 μm) whose power is not dissipated by interaction with any gas molecules and so diff raction will not take place. Th e beam stays coherent. Using up CO2 gas will reduce excess carbon emissions on Earth and bring down global warming also.Th us a temperature and a pressure diff erence created by a CO2 laser is enough to invite these clouds to move towards an opposite region and cause rainfall.

Biography:

Ulrike Willer has studied Physics at Christian-Albrechts University in Kiel and completed her PhD in the year 2001 at Clausthal University of Technology, Germany. She is Researcher at the Energy Research Center and Clausthal University of Technology. She has published more than 45 papers in reputed journals and has been serving as Progam Comittee Member for different scientifi c conferences. Her main research interest focuses on mid-infrared spectroscopy, photoacoustics and sensor design.

Abstract:

Photoacoustic spectroscopy relies on the temporally modulated energy input into a gas via absorption and the subsequent transfer into a sound wave that is measured. Th is transfer of energy from vibrational into translational modes is highly dependent on collision partners and linked relaxation rates. For quartz-enhanced spectroscopy (QEPAS) a micro-tuning fork is used as a transducer instead of a conventional microphone and the modulation of the excitation laser is done at the resonant frequency of the tuning fork for signal enhancement. However, it is not only possible to drive the tuning fork into oscillation by the photoacoustically generated acoustic wave but also by applying a modulated voltage. With these two diff erent driving forces, either applied simultaneously or subsequently, it is possible to gain more insight of the properties of the gas and the relaxation dynamics. Th is is especially valuable if the background gas and with it the collision partners, density, velocity of sound and relaxation rates change and a variation in signal cannot unambiguously attributed to a variation in concentration. It will be discussed how the photoacoustic interaction can be used to promote an originally electrically induced tuning fork oscillation or to fasten its fading, which enables the measurement of times rather than intensities.

Biography:

S S Bayya received his PhD in Ceramics from Alfred University in 1992. He is a Research Scientist in the Optical Science Division at the Naval Research Laboratory (NRL) since 1994. His research interests include transparent ceramics, bulk optics and IR fi bers for various optical applications. He currently heads the Optical Materials section at NRL. He has >50 publications and holds 30 patents on optical materials.

Abstract:

Chalcogenide glasses, with their high refractive indices, low phonon energy, high nonlinearity and excellent transmission in the infrared (IR) region, make them ideal for incorporation into various civilian, medical and military applications such as infrared detectors, infrared lenses, planar optics, photonic integrated circuits, lasers and other non-linear optical devices. Chalcogenide glasses have also been widely studied for use in numerous potential optical fi ber applications such as fi ber lasers, amplifi ers, bright sources, as well as passive solid and hollow core IR fi bers for laser transmission. Although stable, low-loss chalcogenide based fi bers with minimum loss of <0.1 dB/m have been demonstrated, the chalcogenide based fi bers suff er from absorption and scattering losses mainly caused by impurities related to hydrogen, carbon and oxygen. Great eff orts have been made in reducing optical losses using improved chemical purifi cation techniques, but further improvements are needed in both purifi cation and fi berization technology to attain the theoretical attenuation. We have also designed and developed negative curvature, anti-resonant fi bers and demonstrated record low loss in the 9.75 – 10.5 μm range. In this paper, we review our recent eff ort in the development of low loss chalcogenide fi bers, by describing the various purifi cation methods and their impact on the optical fi ber loss and discuss the potential future outlook for these fi bers.

Biography:

A Seteikin studied Physics at the Pedagogical University in Blagoveschensk. He has received his PhD in Physics in 2000. Currently, he is a Professor at the Department of Physics of the Amur State University in Blagoveschensk. His scientifi c background is in the fi eld of Laser - Tissue Interaction and Biophysics. In his work, he is using experimental and computational techniques. He has national and international collaborations in Physics and Life Science research.

Abstract:

The aim of this work was to evaluate the temperature fi elds and the dynamics of heat conduction into the skin tissue under several laser irradiation conditions with both a pulsed ultraviolet (UV) laser (λ=337 nm) and a continuous-wave (cw) visible laser beam (λ=632.8 nm) using Monte Carlo modeling. Finite-element methodology was used for heat transfer simulation. Th e analysis of the results showed that heat is not localized on the surface, but is collected inside the tissue in lower skin layers. Th e simulation was made with the pulsed UV laser beam (used as excitation source in laser-induced fl uorescence) and the cw visible laser (used in photodynamic therapy treatments), in order to study the possible thermal eff ects.

Biography:

Izumi Nishidate is working as an Associate Professor at the Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology. His research spans the interdisciplinary fi elds of Biomedical Optics with particular emphasis on the development of new techniques for medical measurement, imaging and diagnosis. His major areas of activity include diffuse refl ectance spectroscopy, spectral imaging, analysis of light transport in biological tissues and functional imaging of various organs. He received his PhD (2004) degree in Mechanical Systems Engineering, from Muroran Institute of Technology, Japan. He has authored/co-authored over 200 refereed journal articles, book chapters and conference/symposia proceeding articles.

Abstract:

Quantitative assessment of optical properties is important for monitoring metabolism, viability and physiological conditions of in vivo biological tissues. Diff use refl ectance spectra of living tissues refl ects the optical absorption spectra of biological chromophores (i.e., oxygenated hemoglobin, deoxygenated hemoglobin, bilirubin, cytochrome c oxidase, and melanin) and the light scattering spectra of tissues. Diff use refl ectance spectroscopy (DRS) has been widely used for the evaluation of chromophores in living tissue. Th e multispectral imaging technique is a useful tool for extending DRS to the spatial mapping of the chromophores and tissue morphology. Th is can be simply achieved by a monochromatic charge-coupled device (CCD) camera with narrowband fi lters and a white light source, which has been used to investigate the physiological conditions in living tissues such as blood perfusion, oxygenation state of hemoglobin, and melanin content. In clinical conditions, simpler, more cost-eff ective and more portable equipment is needed. Th e digital red, green, blue (RGB) imaging is a promising tool for satisfying these demands for practical application. Imaging with broadband fi lters, as in the case of digital RGB imaging, can also probe spectral information without mechanical rotation of a filter wheel. We have developed an simple imaging technique with a digital RGB camera for in vivo functional imaging of biological tissues. Th e experimental results indicated the ability to evaluate the physiological reactions and hemodynamics in rats and humans.

Biography:

Yongsoo Lee has completed his Medical degree at Yonsei University, South Korea. He is the Co-founder and Co-CEO of Oh and Lee Medical Robot, Inc. and affi liated to Yonsei YL Laser Dermatology and Plastic Surgery in South Korea. He has published many papers in respected journals and has served as an Editorial Board Member of medical journals. He also served as the sole Editor of “Scars and Scarring: Causes, Types and Treatment Options,” published by Nova Biomedical, New York, USA.

Abstract:

Studies on laser emission made the application to human skin possible. However, even though the signifi cance of irradiation has been recognized through adverse eff ects, such as post-laser burns and spotty hypopigmentation, few studies have been performed on laser irradiation. Excessive overlap of laser beams over a short period of time causes burns, while excessive overlap over a long period of time (days) results in spotty hypopigmentation, even with carefully-set emission parameters. Th is small fraction of adverse eff ects may be preventable through the use of robotic laser irradiation. Last April, in San Diego, CA, USA, a comparative study on manual and robotic irradiation was presented at the 37th Annual Conference of the American Society for Laser Medicine and Surgery. Th is study entitled as “Comparative Analysis of the Evenness of Laser Irradiation by a Robot vs. Human Hand: A Pilot Study of the Implication on the Eff ectiveness and Safety of Energy-Based Medical Devices”, demonstrated that robotic irradiation was more consistent and even compared with manual irradiation at frequencies of 10 Hz and 30 Hz.  Moreover, the inconsistency of manual irradiation at frequencies of 10-30 Hz was demonstrated, while the robot demonstrated no statistical inconsistency at 10-30 Hz. Truly even laser beam irradiation of three-dimensional surfaces, such as the human face requires a high degree of precision and consistency, as the curvature varies from one point to another. Studies on laser irradiation have been nearly impossible, because of the inaccuracy and inconsistency of the human hand. As inconsistency and imprecision can be overcome with robotic irradiation, new study subjects have arisen for investigation of the eff ects of irradiation patterns on clinical outcomes. Robotic irradiation would enable us to achieve quicker and better outcomes, as well as to prevent the adverse eff ects described above.

Biography:

Masahiro Motosuke obtained his PhD in 2006 from Keio University. He joined the Department of Mechanical Engineering at Tokyo University of Science, and then was in Department of Micro/Nanotechnology at Technical University of Denmark. He is currently an Associate Professor of Tokyo University of Science from 2012. His research interest is on the development of biomedical optical sensing and control technology in advanced lab-on-a-chip platform, including external-fi eld-induced liquid/particle/cell handling.

Abstract:

Optical manipulation of small objects, e.g., particle and cells, has been widely exploited as a fundamental research tool in biochemical analysis for molecules or cell screening. However, utilization of optical force relying on controlling radiation pressure to the targets basically needs fi ne adjustment of optics so that this technology has not been used in Point-of-Care (POC) diagnostics including advanced Lab-on-a-chip (LOAC) platform that is drastically developing fi elds with the aid of micro/nanofabrication. In out study, possibility of optical manipulation for particles or calls in microfl uidic systems without any optical elements was investigated. Firstly, the use of scattering force was considered. Th is allows us to use low-evergy-density light for manipulation. Th en we exploited microfabricated integrated optics which gently focused iraddiated light to targets in microchannel to promote mobility of the targets. Our approach can expand the use of optical force in simpler way toward highly functionalized POC diagnostics based on LOAC platform.

Biography:

Albrecht Lindinger has earned his PhD on helium droplet spectroscopy in Göttingen in the group of J-P Toennies and completed his Post-doc term in Berkeley in the group of D Neumark. He received his habilitation in the fi eld of coherent control at the Freie Universität Berlin in the group of L Wöste and is now working as a Lecturer in the Institute of Experimental Physics at the Freie Universität Berlin. He has published 80 peer-reviewed papers in reputed journals. His main scientifi c interests are laser optics, coherent control, and biophotonics

Abstract:

Laser pulse shaping for control of photo-induced molecular processes has attained considerable success in recent years. It became most exciting when pulse shaper set-ups were employed to generate tailored pulses, which optimally drive the induced processes. Lately, polarization pulse shaping was explored to examine the vectorial character of the light fi eld. Novel pulse shaping schemes for simultaneous phase, amplitude and polarization control were designed and a parametric subpulse encoding was developed. Th ereby, the physically intuitive parameters like chirps and polarization states of subpulses can be controlled. Th is yields new perspectives of utilizing all properties of the light fi eld in the pulse modulation. Currently, pulse shaping methods are increasingly used to investigate biologically relevant systems. Th ereto, pulse shaping is applied to multi-photon excitated fl uorescence, which enables to exploit intrapulse interference eff ects. In this contribution improved fl uorescence contrast between dyes is reported by two-photon excitation with polarization shaped laser pulses behind a kagome fi ber utilizing the anisotropy of the dye molecules. Particularly phase and polarization tailored pulses were employed for two-photon excited fl uorescence of dyes in liquid behind the kagome fi ber. The distortions due to the optical fi ber properties were precompensated to receive predefi ned polarization shaped pulses at the distal end of the kagome fi ber. Th is enabled to optimally excite one dye in one polarization direction and simultaneously the other dye in the other polarization direction. Th e presented method has a high potential for endoscopic applications due to the unique properties of kagome fi bers for guiding ultrashort laser pulses.

Biography:

Victor Kärcher has completed his Bachelor’s in Physics from the University of Münster, Germany. He works on the simulation of x-ray optics in the Group of Helmut Zacharias at the University of Münster.

Abstract:

For the High Energy Density Instrument (HED) at the European XFEL a hard x-ray split-and-delay unit (SDU) is built covering photon energies in the range between 5 keV and 24 keV. Th is SDU enables time-resolved x-ray pump / x-ray probe experiments as well as sequential diff ractive imaging on a femtosecond to picosecond time scale. Th e set-up is based on wavefront splitting that has successfully been implemented at an autocorrelator at FLASH. Th e x-ray FEL pulses will be split by a sharp edge of a silicon mirror
coated with Mo/B4C and W/B4C multilayers. Both partial beams then pass variable delay lines. For diff erent wavelengths the angle of incidence onto the multilayer mirrors is adjusted in order to match the Bragg condition. Hence, maximum delays between +/- 1 ps at 24 keV and up to +/- 23 ps at 5 keV will be possible. In order to evaluate the infl uence of the device on experiments with focused hard x-ray pulses, time-dependent wave-optics simulations have been performed by means of Synchrotron Radiation Workshop (SRW) soft ware for SASE pulses at hv = 5 keV. Th is soft ware tool has recently been applied to assess the capability of the SDU to measure the temporal coherence properties of hard xray FEL-pulses. For this earlier study, diff raction at the beam splitter and a onedimensional cut through the surface profi le was taken into account. At the HED instrument, the XFEL radiation will be focused by means of compound refractive lenses (CRL) in order to perform experiments with intense, focused hard x-ray pulses. Th e results of these experiments severely depend on the fl uence and the spatial shape of the beam that is obtained in the focal area. Th erefore, in this paper the impact of wave-front distortions on the spatial intensity profi le in the focus is analyzed. For this purpose, the entire optical layout of the SDU, including diff raction on the beam splitter edge and the two-dimensional surface profi les of all eight mirrors are taken into account. Th e XFEL radiation is simulated using the output of the time-dependent SASE code FAST. For the simulations diff raction on the beam splitter edge as well as height and slope errors of all eight mirror surfaces are taken into account. Th e impact of these eff ects on the ability to focus the beam by means of compound refractive lenses (CRL) are analyzed.

Biography:

Priyalal Stephen Wijewarnasuriya received his Ph.D. in Physics from the University of Illinois at Chicago. He was a member of technical Staff at the Rockwell Scientifi Center, CA and was dedicated to demonstration of novel, large-format infrared focal plane arrays for tactical and strategic military applications as well as for astronomy using HgCdTe alloy. He is currently leading the development of the next generation of infrared materials and devices at the U.S. Army Research Laboratory (ARL), Adelphi, MD. He is the Team Leader of "II-VI Materials and Devices Team". Dr. Wijewarnasuriya has authored or co-authored over 100 papers in the open technical literature, four book chapters and has presented his work at numerous national and international conferences. Currently, Dr. Wijewarnasuriya serves as a member of the organizing Committee for two international conferences in the infrared technology area.

Abstract:

Mercury cadmium telluride (HgCdTe) alloy is of great importance in sensing radiation from the near infrared (c ~ 1 μm) to the very long wavelength infrared (c ~ 15 μm). Much of the HgCdTe-related research and development work is carried out for cooled operation. Intrinsic carriers play a dominant role, especially at long-wavelength (LW 8 μm to 12 μm cut-off ) material near ambient temperatures due to high thermal generation of carriers. Th is results in low minority carrier lifetimes due to Auger recombination processes. Consequently, this low lifetime at high temperatures results in high dark currents and high noise. Cooling is one means of reducing this type of detector noise. Th e challenge is to design photon detectors to achieve background-limited performance (BLIP) at the highest possible operating temperature, with the greatest desire being operation close to ambient temperature. This paper present a path to achieve BLIP LW HgCdTe at twice the operating temperature of current 80K LW HgCdTe technology. High operating temperature LW devices would result in several advantages to an infrared imaging system. Th is technology will off er half the cool down time than the present technology for greater battle fi eld survivability with faster fi rst “image out” and less than half the power consumption (2 Watts vs 5 Watts). Th is will lead to dramatic reduction in size, weight and power resulting reduced cost (SWaP-C).

Biography:

Morad Khosravi Eghbal is currently a Graduate Research Assistant and a PhD Candidate at the Photonics Research Lab at the University of Texas at San Antonio. His research focus is on the millimeter wave radio-over-fi ber communication, optical coding and multi-wavelength transmission methods for 5G architecture.

Abstract:

In the past few years, because of the introduction of new bandwidth-demanding services and applications through mobile phone communication, demands for a higher capacity that can support execution of such services has increased substantially. An eff ective method to increase the capacity is to move to the higher working frequency bands (to the millimeter wave region (>30 GHz)). Th is region has an inherently higher capacity, plus is more secure and less occupied. However, millimeter waves when transmitted over the air are prone to atmospheric losses and are severely attenuated at a relatively short propagation distances. Th us, transmission of such signals through an optical fi ber link will simultaneously preserve the security, augmented capacity and yet the propagation distance without the signals being distorted and with relatively much longer than over-the air propagation. To add to the capacity even further, two of the well-established methods of increasing the capacity were merged in this work. First, was to increase an optical network’s capacity by employing several wavelength channels to transmit optical signals in parallel. Depending on the number of wavelength channels, the capacity of the system will be multiplied. Th e other was optical encoding that can help to further increase the capacity of the system and accommodate more channels to be transmitted simultaneously. Th is method assigns diff erent optical codes to each channel that is identical and can only be decoded individually. The is work, utilizes above methods to increase the capacity of a W-band radio-over-fi ber WDM-over- OCDMA system to accommodate more users per channel.

Biography:

Ousmane I Barry is pursuing his fi nal year PhD at Nagoya University (NU) in Japan. He is also a Research Assistant at NU’s Institute of Materials and Systems for Sustainability (IMaSS). His research interests lie in the epitaxial growth and characterization of III-nitride compound semiconductor materials for optoelectronic and high-power device applications.

Abstract:

Nonpolar (m–plane) nitride heterostructures-based electronic devices are, unlike their polar (c-plane) counterparts, devoid of spontaneous polarization and piezoelectric fi elds. Th is unique feature makes nonpolar nitride materials very promising candidates for normally-off enhancement mode transistors which are highly demanded in safe power switching operation and also for very stable light emitters owing to the suppression of the quantum confi ned Stark eff ect. Recent breakthroughs in the bulk GaN growth technology have made low defect m–plane GaN substrates commercially available, paving the way for higher-quality homoepitaxial GaN growth and the development of vertical devices. However, the growth of nominally on-axis homoepitaxial GaN layers by metal-organic vapor phase epitaxy (MOVPE) on these native substrates generates wavy surface reliefs characterized by three-dimensional four-sided pyramidal hillocks which are detrimental for device fabrication. In addition, a higher unintentional impurity incorporation in non-polar nitride fi lms hinders device performance and reliability. In this talk, we present a technique to reduce the formation of pyramidal hillocks on the homoepitaxial m-GaN fi lms. Smooth surfaces with very low density of hillocks are achieved under high V/III ratio and exclusively N2 carrier gas. Th e electrical properties of m-GaN fi lms were found to be dependent on the surface morphology. A clear improvement of the electrical properties can be observed by suppressing the hillocks. Subsequently, impurities concentrations in m-GaN fi lms were signifi cantly reduced with V/III optimization and pure N2 carrier gas as confi rmed by SIMS analysis. Th ese results show good prospects for the development of next-generation electronic devices on non-polar GaN materials.

Biography:

Mohammad A Z Al-Khateeb has received his BSc in Communication and Software Engineering from Balqa’ Applied University, Jordan. Then he received his MSc degrees in Photonics Networks Engineering, Erasmus Mundus double Master’s degree, from Scuola Superiore Sant'Anna and Aston University. He is currently working towards PhD degree from Aston University under the supervision of Prof. Andrew Ellis. He is currently working across multiple projects, participated in organizing outreach activities such as LightFest (an International Year of Light event in Birmingham) and he is working on industrial contracts. He has authored/ co-authored over 12 publications and he is leading the development of theoretical tools and experimental demonstrations to exhibit the benefi ts of Optical Phase Conjugation in optical communication systems.

Abstract:

The fundamental performance limits of coherent optical transmission systems can be observed by a simple optimization between the linear noise and the nonlinear noise generated within the system. Optical Phase Conjugation (OPC) is considered to be one of the promising techniques to compensate for optical fi ber’s dispersion and nonlinearity that cause crosstalk between signals traveling through long-haul optical transmission systems, nonlinearity compensation can lead to signifi cant information capacity and distance reach expansion of optical fi ber transmission links. To get the full benefit from the deployment of OPC in optical transmission systems, a few considerations must be taken into account, such as: power profi le symmetry, fi ber’s dispersion slope and Polarization Mode Dispersion (PMD). In this contribution, we will present our simplifi ed theoretical predictions of optical fi ber transmission systems performance that deploy mid-link OPC and multi- OPC and we will show that the introduction of multi-OPC in an optical transmission system will minimize the impact of uncompensated/nondeterministic signal-signal nonlinear interactions due to fi ber’s PMD and signal-noise interactions. We will show wide range of simulation and experimental results that validate the theoretical predictions of system’s performance for various types of links: dispersion managed, dispersion unmanaged, discretely amplifi ed systems and distributed Raman amplifi ed systems. Also, we will present an extensive experimental study shows that the deployment of mid-link OPC can provide a signifi cant reach improvement in asymmetric lumped optical fi ber links when optimizing the span length.

Biography:

Simeon Bogdanv has received his PhD from the group of Manijeh Razeghi at Northwestern University in 2014. He is currently a Post-doctoral Research Associate at Purdue University in the group of Vladimir M Shalaev. His research interests include optoelectronic devices and quantum nanophotonics. His scientific achievements include the fabrication of InAs/GaSb superlattice photodetectors operating at 10 μm with the lowest dark current and the world’s brightest singlephoton source based on a nitrogen-vacancy center in diamond. He is Member of the Optical Society of America and serves as Reviewer for journals such as Optics Express, Optics Materials Express, Optics Letters and Nanophotonics.

Abstract:

Integrated quantum photonics imposes very stringent and oft en contradictory requirements on the design of integrated optical components. Plasmonic materials promise to confer novel properties to integrated quantum devices, that are not achievable with dielectric materials, such as nanoscale footprint, ultrafast operation and very strong light-matter interaction. In this talk, we will focus on the advantages of plasmonics for producing single photons. Our single-photon source is based on a nitrogen-vacancy center in diamond in a gap-plasmon cavity. It features a 200-fold speed-up in emission and a 30-fold increase in detected photon count compared to a reference source made without the plasmonic cavity. We discuss the potential of this enhancement mechanism for the engineering of tomorrow’s quantum photonic systems.

Biography:

Johannes Hepp has completed his MSc in Material Science from Friedrich-Alexander-University Erlangen-Nuremberg (FAU) and started working on his PhD as Reseacher at Bavarian Center for Applied Energy Research (ZAE Bayern) in February 2015. He is a Doctoral Researcher at the School of Advanced Optical
Technologies Erlangen (SAOT) and has authored/coauthored three publications.

Abstract:

Optical measurement techniques open the door to a wide variety of quality inspection tools. However, the number of customizable settings, like e.g. excitation sources or optical fi lters, is immense. For the quality inspection of thin film photovoltaics, we developed a Matlab based analysis tool in order to investigate as many parameters-potentially obtained by diff erent metrology methods-as possible, in a fast and reproducible way. Th is tool automatically executes procedures like peak wavelength detection of luminescence spectra (an indicator for material composition), hot spot detection in IR images (an indicator for recombination losses) and many mathematical combinations of multiple images taken under varying conditions. One application of this approach was to separate the eff ects of material composition from the infl uence of the defects on the performance of a photovoltaic module. Th e combination of these two performance indicators showed a good correlation to
the open circuit voltage of the device, proving the relevance of this analysis approach. Furthermore, the tool was capable of capturing further refi nements following from hardware improvements like the combination of images taken with special IR fi lters. Th is allowed us to combine the benefi ts of spectral and spatial resolution, which could be used in order to selectively identify certain chemical substances and their distribution in the sample of interest. Th e soft ware applies the scripted processing tasks successively on all samples of a measurement series within minutes, thus enabling high throughput inline measurements. Th e implemented graphical user interface (GUI) allows for a fl exible and user defi nable handling.

Biography:

Farzad Rezaei has graduated with a PhD in Fiber and Polymer Science from the College of Textiles at North Carolina State University. Currently, he works at the College of Textiles as a Post-doctoral Research Scholar. The focus of his research is on polymeric coatings, surface modifi cation and plasma science.

Abstract:

This research presents a comprehensive study of surface modifi cation of polyethylene terephthalate fi lm substrates to improve its adhesion properties using a large area atmospheric plasma. Diff erent aspects of this study includes: analysis of the physical and chemical characteristics of the plasma as well as the substrates and evaluation of adhesion of an acrylate based hard coating onto PET substrates. PET is chemically inert to most coatings, but atmospheric plasmas can modify the surface in a manner that is compatible with high throughput manufacturing. First, optical emission spectroscopy was employed to analyze the plasma in terms of its chemical composition as well as physical characteristics such as electron temperature and density. Th is section estimates electron temperature of 0.2-0.4 eV and density in the order of 1014-1015 cm-3 for the studied plasmas. Second, various plasma gas mixtures with helium as the seed gas mixed with fraction of oxygen and/or nitrogen (0.5-1.1 v%) were used to carry out the surface treatment of the substrates at diff erent exposure doses between 15 to 75 J cm-2. Post-treatment characterization by XPS, AFM and a goniometer show that the surface becomes enriched with oxygen, rougher and more wetting depends on the power and composition of the plasma. Lastly, standard adhesion 180° T-peel tests indicated improved adhesion aft er treatment.

Biography:

Marek VostÅ™ák is a PhD candidate in the fi eld of Laser Technologies. In 2010, he has received his Master’s degree in Applied Physics from the University of West Bohemia and he has been a Researcher in the New Technologies Research Centre since then. His research is focused on laser cladding and laser remelting and utilization of thermography measurement in these technologies. He is an author and co-author of numerous outcomes of applied research and some notable publications in this area, the most recent one is “Diagnostic of laser remelting of high velocity oxygen fuel sprayed stellite coatings using an infrared camera
published in Surface and Coatings Technology volume 318 (2017): 360–364.

Abstract:

Laser remelting of thermally sprayed coatings is a promising possibility how to improve their functional properties such as wear and corrosion resistance. To achieve the optimal results and the desired depth of remelting, it requires a precise control of laser process parameters. However, any suitable control of laser remelting process by means of infrared measurement was yet not described. In this study, a high-power diode laser was used to remelt the HVOF sprayed stellite coatings. Samples with a diff erent coating/substrate thickness ratio were utilized and by variating the process speed the diff erent depth of remelting was achieved. The remelting process was recorded by the combination of a Long Wavelength Infrared (LWIR) and a Near Infrared (NIR) camera. Th e experiment was designed to fi nd the most suitable method for diagnostics of a remelting process. The possibilities of evaluation of a temperature fi eld in the interaction zone are presented. Th e width of melting pool is calculated from the evaluated temperatures and then correlated with the measured depth of remelting. Th e approximations of their mutual dependence show very high correspondence. It indicates that this measurement can be used for controlling of the depth of remelting, regardless of the samples dimensions.

Biography:

Maybritt Kuehn has studied Material Science at the Technische Universitaet Darmstadt, Germany. With her diploma thesis she started to work in Jaegermann’s group, completed her PhD there and continued with Post-doctoral studies. She did her PhD thesis in cooperation with the Merck KGaA, Darmstadt, Germany, at  Innovationlab Heidelberg, Germany and focused on pholelectron spectroscopy. In her PhD thesis, she investigated the infl uence of energetic alignment at organic/ organic-interfaces on the current-voltage behaviour of OLEDs.

Abstract:

Organic light emitting diodes play an important role in our daily life, e.g. as displays in smart phones. Nevertheless these modern multilayer devices oft en show unexpected eff ects during operation. One of these phenomena - the thickness dependent onset voltage shift - is topic of this contribution. Th e investigations concentrate on two OLEDs that only differ in the emission layer but show an entirely diff erent current-voltage behaviour. If the emission layer consists of the triplet host TH-A a shift in onset voltage in case of emission layer thickness variation can be observed. Using TH-B in the emission layer, an isomer to TH-A, the onset voltage remains unchanged. In a previous publication, we could show that an electric interface fi eld is responsible for the thickness dependent onset voltage shift . Th e interface fi eld is already present in the currentless case. Th is presentation now deals with the origin of such an interface fi eld. Th erefore the energetic alignment at the internal interfaces in the two diff erent devices is measured by performing in-situ step by step interface experiments using photoelectron spectroscopy. In case of the device showing no onset voltage shift a fl at band situation is measured, while in case of the other device (where there is the onset voltage shift ) the formation of space charge regions is detected. A further stack modifi cation proofs that the band bending at the hole injecting interface into the emission layer is responsible for the onset voltage shift .

Biography:

Hongyang Wang received his PhD in Materials Manufacture Major from Dalian University of Technology, China. Now, he is working as an Associate Professor of
Dalian University of Technology, a Deputy Director of Key Laboratory of Liaoning Province in China. He is mainly committed to lights welding and dissimilar welding process. His research has brought him more than 20 papers in reputed journals with more than 200 of SCI citation.

Abstract:

The pluse laser-tungsten inert gas hybrid welding method was adopted to realize the welding dissimilar alloys process. The welding modes in the laser-arc hybrid welding lap joint were changed with the varying of laser and arc parameters, which made obviously eff ects on the dissimilar joints. In Ti and steel dissimilar welding lap joint with Cu interlayer, the welding mode in both of Ti and steel fusion zone were in conductive mode and the thickness of the intermetallic was limited by the accurate control of the welding heat. In Mg and Al alloys dissimilar welding lap joint with Ni interlayer, the welding mode in Mg fusion zone was in keyhole mode and Al fusion zone in conductive mode and the intermetallics was inhibited by the welding mode and interlayer. In Al and steel dissimilar welding lap joint with Cu interlayer, the welding modes in both of Al and steel fusion zone were in keyhole mode, but the thickness of the Al-Fe intermetallic was less than 10μm, which was reduced by the hybrid eff ect of the Cu interlayer and the welding sources. Th e welding mode should be changed by the character of the dissimilar metals. Th e formation and distribution of the intermetallic was decided by the welding sources, base metal and the welding process, which made obvious eff ect on the property of the joint.

Biography:

Najmeh Abbasirad is currently pursuing her PhD in Nano-optics group at the Institute of Applied Physics, Friedrich Schiller University Jena under supervision of Prof. Thomas Pertsch. At present her research focuses on near-fi eld optical microscopy and developing dual-probe SNOM for characterization of optical nanostructures

Abstract:

Scanning near-fi eld optical microscopy (SNOM) is a powerful technique to visualize optical phenomena within the nearfield region of optical nanostructure. In standard aperture SNOM measurements, there is a small aperture which serves as a point-like emitter or detector of light. In dual-probe SNOM, there are two aperture tips which simultaneously illuminate and collect the light on a surface of nanostructures. In the dual-probe confi guration, both illumination and collection resolution depends on the aperture size and can overcome the diff raction limit. Furthermore, the measurement signal is not infl uenced by background radiation stemming from an illumination laser spot. Although the dual-probe SNOM measurements have been reported for the measurement of surface plasmon polaritons (SPPs) propagation as well as local carrier dynamics in quantum wells, due to complications of dual-probe SNOM measurements, this technique is not yet a common near-field characterization method. Recently, we have introduced a fully automated and robust dual-probe SNOM technique which has facilitated the robust implementation of the measurement. In this technique, a reliable collision avoidance scheme only based on shear force interaction between two tips is employed. Th e fully automated dual-probe technique not only simplifies the application of dual-probe SNOM, but a low noise electronic also leads to considerably improved data acquisition. In this work, we demonstrate the capability and stability of the method by measuring SPPs propagation for near-infrared excitation. Th e illumination probe excited SPPs on a gold fi lm at 1550 nm wavelength. Th e SPP propagation is mapped on an area around the illumination probe by raster scanning of the collection probe. A computer-controlled collision avoidance scheme prevents the collision of two probes. Th erefore, the optical signal is mapped without user interference. Th e fully automated dual-probe SNOM could open up a new possibility to quantitatively investigate and image the optical fi eld interaction with plasmonic and dielectric devices as well as surface wave propagation.

Biography:

Zanozina Ekaterina has completed her PhD from Voronezh University and State Research Center of Russian Federation Troitsk Institute For Innovation and Fusion Research. She is now a Post-doctoral Researcher in J Heyrovsky Institute of Physical Chemistry AV ÄŒR in Prague. In the Department of Spectroscopy, she actively participates in solving problems, which mainly include the identifi cation of infrared spectra of atoms and complex analysis of spectral data. She is the author of 11 publications in impacted journals with 37 citations. She presented her results at six international conferences focusing mainly on spectroscopic issues. Her research interests include Rydberg states of atoms and molecules; interaction of electromagnetic radiation with atoms; mathematical and computational physics; time-resolved FTIR spectroscopy and transition probabilities.

Abstract:

Compared with the visible and ultraviolet ranges, fewer atomic and ionic lines are available in the infrared spectral region. Atlases of stellar spectra oft en provide only a short list of identifi ed lines and modern laboratory-based spectral features for wavelengths longer than 1 micron are not available for most elements. In spite of the fact that oxygen is one of the most abundant elements in the universe, very few studies of their spectra in infrared region have been reported. Th e normal system of O I terms available in the NIST atomic spectra database was established more than a half-century ago. Th e present work attempts to address the above issues. We exploited the great advantages of time-resolved Fourier transform spectroscopy, such as its constant high resolution and energy throughput, to record high-resolution spectra of oxygen in a wide domain of 800-13000 cm-1 (0.77-12.5 μm). With the help of recent high-accuracy direct measurements of the 3p level in the UV, we performed a re-optimization of O I level energies. Th is re-optimization uses 146 O I lines in the infrared (including 59 lines not measured previously in the laboratory) to yield more accurate energies of levels with n=4-7, l≤6. For some of these levels, we experimentally found fi ne structure splitting for the fi rst time. Th e line classifi cation was performed using relative line strengths expressed in terms of transition dipole matrix elements calculated with the help of quantum defect theory (QDT). To verify our QDT calculations of dipole transition matrix elements, we checked several QDT-calculated oscillator which
strengthened against the results of other authors. Th e method showed the good agreement with the vast majority of the data listed in the NIST ASD.

Biography:

Iman Sabri Alirezaei received his MSc degree in Applied Physics from Shahid Beheshti University (SBU). He is currently doing his PhD and working as a Research Assistant in Electrical Engineering at Institute of Micro and Sensor Systems, Magdeburg University. His current research interests include CMOS-MEMS devices, micro- and nano-photonic devices, optical fi ber sensors, integrated photodetectors and Lab-on-a-chip.

Abstract:

A silicon-based photodetector array with on-chip integration to tiny fiber strands on a single chip is fabricated using 3D-complementary metal-oxide-semiconductor (CMOS) and microelectromechanical systems (MEMS) technology. The 3D-detector involves a vertical photoactive area as large as the fi ber diameter for direct butt-coupling to the optical fiber. Novel ultra-deep trench isolation with a passivation method is carried out to overcome the leakage current as well as the surface recombination current and the dark current, which arise from the fabrication of the ultra-deep trenches. The passivation method consisting of SU-8 polymer enables to implement the deep trenches with a depth of 30μm for both the vertical photoactive area and the inter-pixel trench isolation in the CMOS process. All pixels in the linear array are held at the same applied reverse voltage, by stacking the interconnection line across the pixels. Besides, a tapered U-groove array is built on the monolithically integrated fi ber couplers platform for chip-level fi ber insertion. Th is detector shows an external quantum efficiency of 63.82%, corresponding to the photoresponsivity of 0.32A/W, at a wavelength of 631nm for 2V reverse bias. The proposed detector array integrated into a fiber bundle is very promising to apply for remote optical fiber sensing applications in harsh environments, where involve high electromagnetic fields or RF signals such as magnetic resonance imaging (MRI) or positron emission tomography (PET).

Biography:

Nadiah Aldaleeli received her BE degree in Physics from the King Faisal University, Saudi Arabia, in 2003 and the Master’s degree in Laser and Spectra from King Saud University in 2008 and her Master's project ( Spectral diagnosis of cancer samples before and after surgery) was awarded the golden medal for the best research in that year. In 2010, she joined the Department of Physics, Aljouf University, Saudi Arabia, as a Lecturer and since 2013, have been with the Department of Physics, Education Collage, Imam Abdulrahman Bin Faisal University, Saudi Arabia, as a Lecturer as well. She is currently at Swansea University for a PhD
program in the fi eld of Nanotechnology and her research interests lie in laser diagnostics and spectroscopy.

Abstract:

An important application of Surface Enhanced Raman Scattering (SERS) is the potential of intracellular analysis based on Raman reporters attached to nanoprobes. SERS is an appropriate technique for identifi cation of molecular species of a biological system; measuring local chemical changes at the subcellular level with high spatial and temporal resolution. Measuring pH utilising the enhanced Raman response from pMBA when it has functionalised gold nanoparticles (Au NPs) has attracted signifi cant attentions. Th us, the application of such a system to the measurement of intracellular pH is a key aspect of current development. Th e importance of monitoring the intracellular pH appears in gaining a better understanding of the occurrence and progression of diseases. Herein, the sensitivity of pH nanoprobe based on pMBA functionalised 30 nm Au NPs to the pH changes of the surrounding solutions has been investigated not only with a pure stock solution of pMBA-Au but also when internalised inside Brachionus plicatilis. The preliminary results show that the chemical sensing of the nanoscales probe is maintained when inserted into living cells giving an evidence of the ability of such probe to monitor intracellular pH changes. The sensitivity of such nanoprobe to the pH changes inside the organism is refl ected in the changes of the SERS response of the pH calibration modes at 696 cm-1, 1393 cm-1 and 1702 cm-1 which shows a similar trend to the pure stock solution of pMBA-Au.

Biography:

Junze Li has completed his PhD from Peking University. He is working as the Research Assistant of Microsystem & Terahertz Research Center of China Academy of Engineering Physics (CAEP). He has published more than 20 papers in reputed journals.

Abstract:

Gallium nitride lasers, especially the single-mode distributed feedback (DFB) lasers using Bragg gratings own potential applications in communication systems due to their high-speed modulation. For the blue-violet light, the value of a period of the first-order diff raction grating is about 80 nm. Th is poses a big challenge when forming the high precision grating and nitride overgrowth based on it. We fabricated the fi ne step shape structure of fi rst-order and 3rd order grating by nanoimprint and inductively coupled plasma (ICP) dry etching and we proceeded with an epitaxial regrowth of AlGaN layer with 6% to 12% Al content. Th en we designed a series of gratings with diff erent period, depths and duty ratios to study the influence of grating structure on nano-heteroepitaxy. And we improved the overgrowth by enhancing the growth temperature as high as 1450°C. Moreover, we observed the nucleation and growth process by step-by-step growth to study the growth mode for nitride overgrowth on grating, under the condition that the grating period was larger than the mental migration length on the surface. Th ese samples were analyzed structurally by high-resolution transmission electron microscopy (HRTEM) and spacespectrally by cathodoluminescence (CL). Th e growth dynamics analysis of the nitride nano-epitaxial in this research is one of the frontier areas of nitride photoelectric devices, which is not only meaningful in semiconductor material physics, but also important for related scientifi c researches and applications.

Biography:

Ilkay Demir has completed his PhD at the age of 32 years from Cumhuriyet University, Physics Department. He is the researcher of Nanophotonics Research and Application Center and Department of Nanotechnology Enginnering. He spent 1 year of his PhD at Center for Quantum Devices under supervision of Prof. Manijeh Razeghi. He has published 5 papers in reputed journals.

Abstract:

The growth of thick, high quality and low-stress AlN fi lms on Si and Al2O3 substrates is highly desired for a number of applications like the development of micro and nanoelectromechanical system (MEMS and NEMS) technologies and particularly for fabricating AlGaN based UV-LEDs. UV-LEDs are attractive as they are applied in many areas, such as air and water sterilization, efficient white lighting, high-density optical data storage and military applications such as biological agent detection and non-lineof-sight communication. However, the development of UV-LEDs on Si substrates is highly desired for a series of  reasons like the availability of cheap, large-diameter silicon wafers, the much lower device processing costs, and the possibility of monolithical integration of the UV-LEDs with Si circuitry. In addition, effi cient AlGaN based deep UV-LEDs require layers and substrates which are transparent in UV light. So, it is preferable to grow the AlGaN based deep UV-LEDs active layers on Si  substrates as the Si can be removed by chemical treatment to allow back illumination and avoid the generation and reabsorption of UV light by backside emission. Th ese advantages make silicon an attractive substrate for AlGaN based UV devices. Additionally high quality AlN template on Al2O3 substrate still is the key layer to grow high quality AlN and high Al content AlGaN  materials for DUV applications since AlN substrate price and size are not suitable for mass production.