Day 2 :
Keynote Forum
Simon Fafard
Broadcom, USA
Keynote: Optical to electrical power conversion devices with the highest efficiency ever (Eff > 60%) based on the vertical epitaxial heterostructure architecture (VHESA) design
Time : 08:30-09:00
Biography:
Simon Fafard is Co-founder & President of Broadcom a large public company that recently acquired Azastra and which has been an innovative Canadian optoelectronic company. He has been focused on optoelectronic at uSherbrooke and at Azastra, a corporation that commercialized laser power converter products based on the new VEHSA technology. He has an h-index of 45 and is the inventor of over 30 patents. He raised over $20M of private and venture capital funding and also obtained numerous research grants. He led Cyrium to become a manufacturer of one of the highest performance multijunction III-V solar cells and led Azastra to manufacture the highest performance phototransducer products. As an entrepreneur, he cumulates over 25 years of experience in Optoelectronics and Photonics while developing and commercializing numerous devices and products in the industry at Azastra, Aton, Cyrium, Alcatel Optronics, Kymata, and also in research labs at uSherbrooke, NRC, and UCSB.
Abstract:
Simon Fafard is Co-founder & President of Broadcom a large public company that recently acquired Azastra and which has been an innovative Canadian optoelectronic company. He has been focused on optoelectronic at uSherbrooke and at Azastra, a corporation that commercialized laser power converter products based on the new VEHSA technology. He has an h-index of 45 and is the inventor of over 30 patents. He raised over $20M of private and venture capital funding and also obtained numerous research grants. He led Cyrium to become a manufacturer of one of the highest performance multijunction III-V solar cells and led Azastra to manufacture the highest performance phototransducer products. As an entrepreneur, he cumulates over 25 years of experience in Optoelectronics and Photonics while developing and commercializing numerous devices and products in the industry at Azastra, Aton, Cyrium, Alcatel Optronics, Kymata, and also in research labs at uSherbrooke, NRC, and UCSB.
Keynote Forum
Michelle R Stem
Complete Consulting Services, USA
Keynote: Quantum laser interactions with select silicate specimens
Time : 09:00-09:30
Biography:
Michelle R Stem has a PhD in Materials Science Engineering, MBA in Management and BS in Chemistry. She has done Post-doc Research and continued work as Senior Materials Researcher at Complete Consulting Services, LLC. She applies interdisciplinary expertise through multi-scale analysis, computational modeling and laboratory synthesis to study extremely rare inorganic, complex and semi-conductor (ICS) materials. She researches ICS structural and property variations to discover and ultimately engineer new methods, applications, models, materials and metamaterials with the goal of controlling photonic, phononic, optoelectronic, band gap and other properties. In addition, her research develops materials that save energy (e.g. power differentials for photonic band gap versus electronic materials) and finds alternatives to using up rare resources.
Abstract:
This presentation will show never-before-seen colorful micrographic images of select natural silicate specimens interacting with various laser sources. These micrographs will reveal a closely magnified view of materials with rare properties, such as anti-Stokes upconversions and negative index metamaterials. In contrast to currently available manufactured materials, the natural materials to be presented display these rare properties under conditions in which the currently available manufactured materials cannot function, e.g. ambient temperatures, ambient pressures, no radioactive elements, no heavy metals, no added photons, no electricity and ambient air environment. A goal is to develop materials with the photonic control displayed by these natural materials for applications that include: solar power, space exploration, energy efficiency, stealth technologies, photonic waveguides and data storage/transmission.
Keynote Forum
Nabeel A Riza
University College Cork, Ireland
Keynote: The CAOS smart camera–empowering automotive and surveillance imaging
Time : 09:30-10:00
Biography:
Nabeel A Riza holds a PhD (1989) from Caltech. His awards includes the 2001 ICO Prize, 2001 Ernst Abbe Medal from Carl Zeiss Foundation-Germany, 2009 and 2010 IEEE Distinguished Lecturer Awards and 1994 GE Gold Patent Medal. In 2011, he was appointed as Chair Professor of Electrical and Electronic Engineering, University College Cork (UCC), Ireland. During 2013-2016, he was Dean of UCC School of Engineering. He has published 404 works that include 46 US issued patents and is a 2017 Inductee of the US National Academy of Inventors (NAI).
Abstract:
Multi-pixel imaging devices such as CCD, CMOS and FPA photo-sensors dominate the imaging world. These photodetector array (PDA) devices certainly have their merits including increasingly high pixel counts and shrinking pixel sizes, nevertheless, they are also being hampered by limitations in instantaneous linear dynamic range, inter-pixel cross-talk, quantum full well capacity, signal-to-noise ratio, sensitivity, spectral flexibility and in some cases, imager response time. Recently invented is the coded access optical sensor (CAOS) smart camera that works in unison with current PDA technology to counter fundamental limitations of PDA-based imagers while providing extreme linear dynamic range, extreme image security, extreme inter-pixel isolation and high enough imaging spatial resolution and pixel counts to match application needs. This talk describes the basics of the CAOS smart camera invention using the Texas instruments (TI) digital micromirror device (DMD). The talk highlights recent experimental demonstrations of both white light and multi-spectral CAOS-based imaging including CAOS-mode imaging over a 136 dB linear dynamic range. Novel applications of the CAOS smart camera include automotive and surveillance imaging where smartness to identify vital targets in extreme contrast scenarios is vital for both mobile and stationary system operations.
Keynote Forum
Tianhong Dai
Harvard Medical School, USA
Keynote: Antimicrobial blue light inactivation of pathogenic microbes: State of the art
Time : 08:30-09:00
Biography:
Tianhong Dai is working as an Assistant Professor of Harvard Medical School. His research interest is centered around light-based antimicrobial therapy. In particular, his laboratory has been interested for some time in using antimicrobial blue light to treat multidrug-resistant localized infections. He is the author or co-author of over 80 peer-reviewed publications and has been the PI of NIH R01, NIH R21, DoD, CIMIT as well as grants from other funding sources. He is the Founding Chair of the conference “Photonic Diagnosis and Treatment of Infections and Infl ammatory Diseases (Conference BO113)” at the SPIE Photonics West, BIOS.
Abstract:
As an innovative non-antibiotic approach, antimicrobial blue light in the spectrum of 400-470 nm has demonstrated its intrinsic antimicrobial properties resulting from the presence of endogenous photosensitizing chromophores in pathogenic microbes and subsequently, its promise as a counteracter of antibiotic resistance. Since we published our last review of antimicrobial blue light in 2012, there have been a substantial number of new studies reported in this area. Here we provide an updated overview of the fi ndings from the new studies over the past fi ve years, including the effi cacy of antimicrobial blue light inactivation of diff erent microbes, its mechanism of action, synergism of antimicrobial blue light with other antimicrobials, its eff ect on host cells and tissues, the potential development of resistance to antimicrobial blue light by microbes and a novel interstitial delivery approach of antimicrobial blue light. Th e potential new applications of antimicrobial blue light will also be discussed.
Keynote Forum
Yongsoo Lee
Oh and Lee Medical Robot, Inc, South Korea
Keynote: Combination laser treatment for immature scars
Time : 09:00-09:30
Biography:
Yongsoo Lee 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:
Surgical scar revision (SSR) has been the main treatment modality for scars, with few alternative options until lasers were developed and were found to be useful. Combination laser treatment (CLT) and combined CLT and SSR have not been studied in detail, despite evidence demonstrating that the combination of these modalities could result in statistically better outcomes. Immature scars (IS), a novel class of scars, defi ned as “scars whose features are not yet expressed,” are situated at a treatment nexus between SSR and CLT. Vascular lasers have been shown to improve scar quality with treatment on the suture removal day, while fractional lasers are being tested on scars in early stages. However, there are few studies on early laser treatment of scars and no guidelines for the treatment of IS. Th e recently published article by the author demonstrates how IS need to be treated for better outcomes. Th e study also provides useful guidelines for practitioners, based on statistical analysis. Th e study design and statistical methodology of the study will be presented orally and the results are summarised as follows. Th e outcome of facial scarring is more enhanced than that observed in non-facial scars. Facial scars in patients under the age of 15 exhibited greater results when compared to facial scars in older patients. Th e choice of initial vascular laser used on facial scars, either 532nm or 585nm, had no signifi cant eff ect on scar outcome. Th erefore, it is advised that CLT be initiated as soon as possible aft er stitch removal to improve facial scar outcome. Furthermore, younger patients are expected to have a more improved result than those who are older.
Keynote Forum
Amr S Helmy
Univeristy of Toronto, Canada
Keynote: Integrated hybrid plasmonic devices–the role of 2D materials
Time : 09:30-10:00
Biography:
Amr S Helmy is a Professor at the Department of Electrical and Computer Engineering and the Director for the Center of Quantum Information and Quantum Control at the University of Toronto. Prior to his academic career, he held a position at Agilent Technologies, R&D division, in the UK between 2000 and 2004. At Agilent his responsibilities included developing InP-based photonic semiconductor integrated circuits and high-power lasers. He received his PhD and MSc from the University of Glasgow with a focus on photonic devices and fabrication technologies, in 1999 and 1995 respectively.
Abstract:
Hybrid plasmonic devices and the associated circuits, with applications in data communications will be discussed. In addition, the role of 2D materials in this platform will be highlighted. Recent advances in the development of a range of 2D materials brings signifi cant opportunities and challenges to photonic circuits. Because of their thicknesses, when compared to optical wavelengths in the visible and infrared, 2D materials physically overlap with a small fraction of the guided electromagnetic modes at these wavelengths in an integrated setting. In this talk, a new approach to profi t from 2D materials in integrated planar setting through the utilization of hybrid plasmonic structures and anisotropic meta-materials will be discussed. Due to the dissipative nature of plasmonic modes there is an inherent trade-off between the propagation losses and modal confi nement in their implementation. Th is talk will also demonstrate an eff ective approach that utilizes hybrid plasmonic modes to alleviate the trade-off associated with their loss behavior and the modal confi nement factor. Th is new approach holds promise to provide eff ective, nano-scale photonic devices using 2D materials, with losses approaching those exhibited by their dielectric counterparts such as Si. Example devices that profi t from this novel architecture include optical modulators, cavities and detectors with designs specially tailored to eff ectively utilize 2D materials. Th e performance metrics and fi gures of merit of this new class of integrated photonic devices will also be described in the talk and compared with other technologies to demonstrate their superiority.
- Optoelectronics
Location: The Five Spot Room
Chair
A G Unil Perera
Georgia State University,USA
Co-Chair
Kenji Murakami
Shizuoka University, Japan
Session Introduction
A G Unil Perera
Georgia State University, USA
Title: Heterojunction detectors for multi-band detection with wavelength threshold extension mechanism
Time : 10:00-10:25
Biography:
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.
Abstract:
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.
Bellet Daniel
University of Grenoble, France
Title: Transparent and conductive materials for opto-electronic applications
Time : 10:25-10:50
Biography:
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.
Abstract:
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.
Kaddour Lekhal
Nagoya University, Japan
Title: Fabrication of nanowires-based devices grown with controlled orientation
Time : 11:05-11:30
Biography:
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.
Abstract:
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.
Yu Zheng
Central South University, China
Title: High precision fast line detection of alignment and coupling for optoelectronic devices
Time : 11:30-11:55
Biography:
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.
Abstract:
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.
S Nitta
Nagoya University, Japan
Title: In situ and ex situ optical characterization of nitride semiconductor crystal for advanced optical and power electronic devices
Time : 11:55-12:20
Biography:
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.
Abstract:
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.
Si-Young Bae
Nagoya University, Japan
Title: Defect reduction of GaN nano rods on hetero-substrates: Behaviors of basal stacking faults
Time : 12:20-12:45
Biography:
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.
Abstract:
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
devices.
Kenji Murakami
Shizuoka University, Japan
Title: Synthesis and characterization of organic mechanoluminescent materials
Time : 12:45-13:10
Biography:
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.
Abstract:
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.
- Optoelectronics.
Location: The Five Spot Room
Chair
Devki N Talwar
Indiana University of Pennsylvania, USA
Co-Chair
Juan Carlos Rendon Angeles
Centro de Investigacion y de Estudios Avanzados del IPN CINVESTAV-Saltillo, Mexico
Session Introduction
Devki N Talwar
Indiana University of Pennsylvania, USA
Title: Spectroscopic phonon and extended x-ray absorption fine structure measurements on 3C-SiC/Si (001) epifilms
Time : 14:45-15:10
Biography:
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.
Abstract:
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.
Juan Carlos Rendon-Angeles
Centro de Investigacion y de Estudios Avanzados del IPN CINVESTAV-Saltillo, Mexico
Title: Insights of the hydrothermal synthesis of scheelite-structured powders in the SrMoO4-SrWO4 system: Structure and luminescence characterization
Time : 15:10-15:35
Biography:
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.
Abstract:
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.
Hao-Hsiung Lin
National Taiwan University, Taiwan
Title: MBE growth of InAs nanowires on Si
Time : 15:35-16:00
Biography:
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.
Abstract:
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.
Masafumi Jo
Laboratory for Advanced Brain Signal Processing, RIKEN Brain Science Institute, Japan
Title: Recent progress of AlGaN-based deep-ultraviolet light-emitting diodes
Time : 16:15-16:40
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.
Abstract:
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%.
Doron Cohen Elias
Soreq NRC, Israel
Title: Extended short wave infrared photodetectors
Time : 16:40-17:05
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.
Abstract:
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.
Takayoshi Katase
Tokyo Institute of Technology, Japan
Title: Room-temperature-protonation-driven optoelectronic device with water-gated thin-film-transistor structure
Time : 17:05-17:30
Biography:
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.
Abstract:
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.
Geoffrey Avit
Université Clermont Auvergne, France
Title: Hydride vapor phase epitaxy growth of III-V nanostructures for high performance devices
Time : 17:30-17:55
Biography:
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.
Abstract:
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.
- Optical Metrology | Surface Enhanced Spectroscopy | Quantum Science and Technology
Chair
Kuniharu Ijiro
Hokkaido University, Japan
Co-Chair
Tatsuo Shiina
Chiba University, Japan
Session Introduction
John G Ekerdt
University of Texas at Austin, USA
Title: Study of low density sites on silicon dioxide surfaces using fl uorescent probes and the role of these sites in nucleation of semiconductor and metal fi lms
Time : 10:00-10:25
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.
Abstract:
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.
Kuniharu Ijiro
Hokkaido University, Japan
Title: Active gap SERS with plasmonic nanostructures on hydrogels for the sensitive detection of biomacromolecules
Time : 10:25-10:50
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.
Abstract:
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.
Tatsuo Shiina
Chiba University, Japan
Title: Non-diffractive beam in random media
Time : 11:05-11:30
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.
Giedre Samuoliene
Lithuanian Research Centre for Agriculture and Forestry, Lithuania
Title: LED’s for horticulture: Novel insights in plant cultivation
Time : 11:30-11:55
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.
Dong Li
Microsystem and Terahertz Research Center, China
Title: Parity detection achieving Heisenberg limit in an SU(1,1) interferometer with coherent and squeezed vacuum input states
Time : 11:55-12:20
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.
Hua Guan
Chinese Academy of Sciences, China
Title: A comparison of two 40Ca+ single ion optical clocks at 5×10-17
Time : 12:20-12:45
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.
Konstantin Lyakhov
Jeju National University, South Korea
Title: Intensification of boron isotopes separation by the laser field manipulation within the method of isotopes separation by selective condensation retardation in overcooled gas flow
Time : 12:45-13:10
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.
- Laser Systems
Location: Paramount Room
Chair
Yanbo Bai
Coherent Inc., USA
Co-Chair
Nasser Peyghambarian
NP Photonics, Inc., USA
Session Introduction
Yanbo Bai
Coherent Inc., USA
Title: Characterization of optically pumped semiconductor lasers in pulsed mode
Time : 14:00-14:25
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.
Simone Borri
CNR-INO Istituto Nazionale di Ottica, Italy
Title: Novel sources and resonators for high-resolution molecular spectroscopy in the mid infrared
Time : 14:25-14:50
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.
Ramesh G Mani
Georgia State University, USA
Title: Hall coefficient sign reversal in metamaterials
Time : 14:50-15:15
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.
Yohei Sato
Tohoku University, Japan
Title: Liquid phase growth of GaSe crystal for highly efficient THz wave generation
Time : 15:15-15:40
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.
Qi Jie Wang
Nanyang Technological University, Singapore
Title: Integrated terahertz photonics and optoelectronics
Time : 15:55-16:20
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.
Cunzhu Tong
Chinese Academy of Sciences, China
Title: High brightness photonic crystal semiconductor lasers
Time : 16:20-16:45
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.
Nasser Peyghambarian
NP Photonics, Inc., USA
Title: Fiber-based sources spanning UV to Mid-IR
Time : 16:45-17:10
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.
Robert L Green
Florida Polytechnic University, USA
Title: Synthesis and structural characterization of the hexagonal anti-perovskite Na2CaVO4F
Time : 17:10-17:35
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.