Biography:

Ivan Bozovic received his PhD in Solid State Physics from Belgrade University, Yugoslavia, where he was later elected a professor and the Physics Department Konrad Altmann has completed his PhD in Physics from the Ludwig-Maximilian University of Munich, Germany, at 1975. The issue of his thesis was the quantum mechanical description of molecular spectra. For this work, he obtained the marking "with excellence". From 1976 to 1991 he was with the industrial company Messerschmitt-Bolkow-Blohm and developed a computer program for the description of a gas dynamic CO2 laser. From 1991 to 1993 he was with the German Aerospace and developed computer programs and published papers concerning laser beam propagation in the atmosphere. In 1993 he founded the company LAS-CAD GmbH with the purpose to integrate different simulation tools, necessary for the analysis of the multi-physics interaction in solid-state lasers, into the commercial program LASCAD. This program provides the laser engineer with the ability of a quantitative understanding of the complicated effects in laser systems. He has over 25 years of progressively responsible experience in computational physics especially in the fi eld of optics. He wrote more than 40 scientifi c publications in molecular physics, propagation engineering and laser technology and applied for 38 patents, of which 15 have been granted. He also wrote programs for the simulation of laser beam propagation in the atmosphere. In 2014 he was becoming Adjunct Professor of the National Engineering Center for DPSSL of the Chinese Academy of Science.

Abstract:

Th e computer program LASCAD provides a unique combination of simulation tools to optimize LASer Cavity Analysis and Design. Especially the following tools are available:

• Th ermal and Structural Finite Element Analysis of thermal eff ects in laser crystals
• ABCD Gaussian Beam Propagation Code taking into account thermal lensing, gain guiding, etc.
• Dynamic Analysis of Multimode and Q-switched operation analyzing the dynamic 3D behaviour of laser beams
• 3D Physical Optics Beam Propagation Code including diff raction, gain dynamics, etc.

An easy to use graphical users interface allows the combined use of these complex engineering tools. In this way, LASCAD helps the laser engineer to overcome the many interacting technical and physical problems he is confronted with when he develops a laser. Especially thermal lensing is of growing importance, due to the tendency to miniaturize laser systems, while
simultaneously increasing power output. Th e eff ect strongly depends on system characteristics, such as material parameters, resonator geometry, pump beam distribution and cooling layout. It interferes with gain dynamics, mode competition, Q-switching and other eff ects, which control beam quality and laser effi ciency in a complicated manner. Based on a numerical simulation of these eff ects, LASCAD™ provides the laser engineer with a quantitative understanding of the characteristics of a resonator design. Th e GUI of LASCAD, as shown in the fi gure, can be used as an optical workbench on the PC, allowing the intuitive design of laser resonators. In this way LASCAD™ helps users to process experimental results without wasting valuable time studying complicated manuals:

• Optical elements, such as mirrors, lenses or crystals can be added, combined, adjusted or removed by mouse clicks
• Astigmatism in the resonator and crystal is automatically taken into account
• Th e program menu makes available thermal fi nite element analysis, Gaussian ABCD matrix code, physical optics code, analysis of the Q-switched operation, computation of laser stability and power output.

Biography:

Baptiste Mot is a CNRS Research Engineer at the Institut de Recherche en Astrophysique et Planétologie (IRAP) in Toulouse. Since 2009 he is the Project Manager of the PILOT balloon-borne experiment. He is also in charge of the system engineering and of the ground end to end tests performed on the payload. He took part in the two fl ight campaigns in Timmins (Canada) and Alice Springs (Australia) and he works on this two fi rst fl ights' data analysis. He is involved in the conception of the satellite LiteBIRD that is the Class-L satellite mission proposed by JAXA, about to be selected by JAXA by the beginning of 2019. LiteBIRD is dedicated to the observation of the polarized emission from the CMB in order to measure the B-mode imprints of primordial gravitational waves from Infl ation. He is the System Engineer of the High-Frequency Telescope that is one of the two telescopes embedded on LiteBIRD.

Abstract:

PILOT (Polarized Instrument for Long wavelength Observations of the Tenuous interstellar medium) is a balloon-borne astronomy experiment designed to study the polarization of dust emission in the diff use interstellar medium in our Galaxy. Th e PILOT instrument allows observations at wavelengths 240μm and 550μm with an angular resolution of about two arcminutes. Th e observations performed during the two fi rst fl ights performed from Timmins, Ontario Canada and from Alice-springs, Australia, respectively in September 2015 and in April 2017 have demonstrated the good performances of the instrument. Pilot optics is composed of an off -axis Gregorian type telescope combined with a refractive re-imager system. All optical elements, except the primary mirror, which is at ambient temperature are inside a cryostat and cooled down to 3K. The whole optical system is aligned on the ground at room temperature using dedicated means and procedures in order to keep the tight requirements on the focus position and ensure the instrument optical performances during the various phases of a flight. We’ll present the optical performances and the fi rsts results obtained during the two fi rst fl ight campaigns. Th e talk describes the system analysis, the alignment methods and fi nally the in-fl ight performances.

Biography:

Fumihiro Dake, Senior researcher, Research & Development Division, Nikon Corporation, entered Nikon Corporation in 2009. He worked as an optical designer from 2009 to 2013. Then, he got to work on research of optical microscopy. He has researched and developed nonlinear optical microscopy.

Abstract:

In fluorescence microscopy, fluorescence lifetime information enables fluorophores with the same emission spectrums and diff erent lifetimes to be distinguished, which can improve molecular discrimination ability. Fluorescence lifetime generally depends on molecular conformation and the manner in which the molecule interacts with its environment, so that fluorescence lifetime imaging can reveal molecular interactions and dynamics at the molecular scale. We propose a time-domain approach for fluorescence lifetime measurements using nonlinear fluorescence microscopy constructed of two-color laser pulses. Our method is based on the pump-probe setup, where wavelengths of the pump and probe beams overlap the absorption spectrum and the fluorescence emission spectrum of the fluorescent dye, respectively and fluorescence wavelength to be detected is different from both wavelengths of incident beams. Nonlinear fluorescence signals generated by fluorescence reduction due to stimulated emission were detectable through a lock-in technique. The signal is produced by the multiplicative combination of incident beams, resulting in an improvement of the three-dimensional optical resolution. In the experiment, we modulated intensities of the pump and probe beams with frequencies of f1 and f2, respectively and demodulated the signal with f1–f2 to extract nonlinear fluorescence signal. Changing the time delay between the two-color pulses enables acquisition of a timeresolved nonlinear fluorescence signal, which directly refl ects the fluorescence lifetime of the sample and is thus applicable to fluorescence lifetime imaging. We also quantitatively demonstrate that nonlinear fluorescence microscopy possesses better optical resolution than conventional laser-scanning fluorescence microscopy. Experimental trials indicated that straightforward fluorescence lifetime imaging with high optical resolution is readily available.

Biography:

Caterina Gaudiuso received her Master Degree (cum Laude) and PhD in Physics from University of Bari (Italy) in 2011 and 2016, respectively. During her PhD, she spent a period of research as visiting PhD student at the Institut für Angewandte Physik of the Friedrich-Schiller-Universität Jena (Germany), under the supervision of Prof. S Nolte. She is currently a Postdoctoral Researcher at the Physics Department, University of Bari and her main research interest is laser ablation with ultrafast lasers. Her research is especially focused on the generation of bursts of picosecond-delayed sub-pulses, the study of the infl uence on the ablation process of the sub-pulse period within the burst and number of sub-pulses in the burst, the onset of damage process and the incubation effect. Recently, she has become interested in the use of bursts of sub-pulses for nano- and micro-structuring of materials, for varying the wettability and tribological properties of surfaces. The products of her research are 3 publications in peer-reviewed journals, 4 conference proceedings and 7 contributed conference presentations.

Abstract:

In this work, we report on an experimental study of the incubation effect during the irradiation of stainless steel with bursts of 650fs laser pulses at 1030nm. A series of birefringent crystals was used to split the pristine 650fs pulses into bursts of up to 32sub-pulses with time separations of 1.5ps and 3ps. Th e number of selected bursts was varied between 50 and 1600. In order to highlight the infl uence of the burst features on laser BM processing, the threshold fl uence was measured for each combination of the number of sub-pulses and time delays within the burst. Th e threshold fl uence in NPM was measured as well, to provide a comparison between the two processing modes. In BM, we found as many values of threshold fl uence as the combinations of the number of bursts and of sub-pulses constituting the bursts set to give the same total number of impinging sub-pulses, while in NPM the threshold fluence has a unique value, once the number of impinging pulses is fixed. Therefore, a dependence of the incubation coeffi cient with the burst features was hypothesized and experimentally investigated by assuming the incubation factor as a burst feature dependent coeffi cient. It was found that incubation effect is higher in BM than NPM and that it decreases with the number of sub-pulses n and for shorter time delays within the burst. Th e Two Temperature Model (TTM) has been adapted to the irradiation with single bursts of up to 4sub-pulses to interpret the experimental results.

Biography:

Madoka Ono has completed her PhD in the year 2004 from Tokyo University. Her PhD research was the study of optically excited states in low-dimensional Mottinsulators by using linear and nonlinear optical measurements. She joined Asahi Glass Company in the year 2004. Her researches since then were; 1. Electronemission properties of Calcium Aluminate electride 2. Improvement of the transmittance and laser-durability of silica glass 3. Study of the glass structures by positron annihilation measurements and 4. Optimization of glass composition and structures to obtain stronger glass with various strengthening processes. She is now working as a senior researcher and a project leader in AGC. She also works as a part-time lecturer of Yokohama National University, teaching glass science and its applications. She is a board member of photonics division of Japanese Society of Applied Physics.

Abstract:

Silica glass had long and intensively been studied due to its technological interest in manufacturing higher-performance optical fi bers. Recently, silica glass formed at high temperature and pressure is attracting much attention due to its physical properties which cannot be obtained by compression at room temperature. For example, the intermediate-range order structure of silica glass which was hot-compressed at several GPa around the glass-transition temperature (Tg ~1400K) was reported to be more homogeneous and is completely diff erent from that of silica glass compressed at room temperature, even though their densities were similar. Th e threshold pressure to trigger the change seemed to decrease with increasing temperature. We have previously reported that the Rayleigh scattering intensity in silica glass can be explained in terms of the voids in the glass behaving as scattering particles. Here, the expression of “void” stands for sub-nanometer size structural empty space, not bubbles. Th e void size was observed to decrease as the fi ctive temperature, Tf (temperature at which the glass network structure is “frozen”), decreased, by using positron annihilation lifetime spectroscopy. Th e decrease of the void size was found to suppress local density fl uctuations which, in turn, led to less intense light scattering. Th us, a decrease of the Rayleigh scattering intensity was expected if a reduction of the void size can be achieved. For industrial usage, pressures of less than 200MPa is desirable since samples of up to one-meter size are obtainable in a ready-made hot isostatic pressure (HIP) machine. Th erefore, we investigated the Rayleigh scattering intensity of hot-compressed silica glass using HIP under its melted phase. As a result, the optical transport properties of the silica glass was largely improved by the process. The lowest Rayleigh scattering loss was obtained for the glass held at 200MPa and 2073K for 4h. Th e observed loss corresponds to 0.07dB/Km at 1.55m, which is about half of the loss in conventional silica glass fi ber. Th e decrease in the loss was well explained in terms of the decrease in the size of the sub-nanometer-sized structural voids. Due to the compressive stress, the refractive index increased simultaneously with the decrease in the void size and the scattering intensity. Th is is very favorable for fibercore media, where high transparency and strong confi nement of light are desired. It is not possible to otherwise get such glass homogeneity (corresponding to such a low Tf) and reduce the Rayleigh loss simply by thermal engineering at standard atmospheric pressure.

Biography:

Xingjun Wang received the BE, ME and PhD degrees from the Dalian University of Technology, China in 1999, 2002 and 2005 respectively. From 2007 to 2009 he was a JSPS Postdoctoral Fellow in the Department of Electronic Engineering, University of Electro-Communications, Japan. In 2009, he joined Peking University and is currently a Full Professor at Peking University, Beijing, China. In 2015, he was selected fi rst Young Yangtse Rive Scholar of China. Now he is devoted into Siphotonics, including the Si-based light source and Si optoelectronic integration chip for high-speed optical communication. He has published more than 150 papers on international journals and conference proceedings. The 80 papers have been SCI indexed. The citation reaches 800 times.

Abstract:

In the process of information technology, as Moore's law becomes more and more close to the limit, it has become inevitable and the consensus to combine microelectronics and optoelectronics to develop silicon-based large-scale optoelectronic integration technology. As the most important part of silicon photonic devices, silicon-based light source still attracted great eff orts. In the traditional research, the erbium-doped materials have played an important role in silicon-based light sources. Recent studies demonstrated that the erbium silicate compound had a high net gain attributable to its high erbium concentration that has no insolubility problem. This paper focuses on the theory, designs, simulations, preparation methods, process and device optimizations of the erbium silicate compound optical waveguide amplifi er and laser. The erbium silicate compound materials with large optical gains can serve as potential candidates for future silicon-based scale-integrated lightsource applications.

Biography:

Fansheng Chen has completed his PhD in the year 2007 from SITP (ShangHai Institute of Technical Physics of CAS). He is the Professor of SITP, a premier optical remote sensing instrument organization. He has published 32 papers in the main academic journals and authorized 10 patents.

Abstract:

The infrared system used for weak point target detection has high encircled energy and the accurate measurement of the intra-pixel response is the key to realize high-precision radiation calibration and combined positioning of the detection system. A variety of test methods have been established to measure the intra-pixel response in the visible detector pixels, such as the spot scan with the microscopy system. However, there are few types of research about the test method of the intra-pixel response of infrared detectors due to its location in the Dewar cold space. In this paper, an intra-pixel response test method for high encircled energy infrared detection photoelectric system is proposed and a mathematical model for intra-pixel response calculation is established. Th e test system consists of a small hole that simulates a point target, a collimator, a turntable and an optical system of the infrared detection system itself. Th e PSF of the optical system is restricted. Based on the established model, the intra-pixel response parameters of the detector's pixels are calculated by the method of grid search and optimized by the cross-validation method. Several pixels are selected to test and the data is collected by scanning 10×10 spots in a single pixel with a diff erent radius of holes. Th e same pixel in the detector is tested with small holes of diff erent radius, the consistent intra-pixel response and PSF of the optical system are obtained, which proves the eff ectiveness of the method. Finally, the internal response function was verifi ed by the geometric positioning method and the error was within 8%.

Biography:

Seiji Okamoto received the BE, MS and PhD in Electrical Engineering from Tohoku University in 2009, 2011 and 2018 respectively. In 2011, he joined NTT Network Innovation Laboratories, Yokosuka, Japan, where he has been engaging in the research and development of the large capacity and low power digital coherent optical transmission systems with high-speed digital signal processing.

Abstract:

Due to the introduction of digital coherent technology which enables us to employ multi-level modulation such as Highspectral-effi ciency (SE) quadrature amplitude modulation (QAM), the capacity over the single mode optical fi ber has dramatically increased in limited wavelength resources. In a deployed network, polarization-division-multiplexed (PDM) 16QAM signal of which amplitudes modulated with 4 levels began to be widely used using the real-time digital signal processor (DSP) and the SE was 5.3bit/s/Hz. As for the highest-order QAM transmission in the laboratory, the PDM-4096QAM signal was successfully transmitted using an optical phase-locked loop (OPLL) technique and the potential SE was reached 15.8bit/s/Hz. Further higher SE can be realized by utilizing the higher-order QAM, however, it needs much fiber amplitude modulation level and results in the reduced noise tolerance. Meanwhile, the probabilistic shaping (PS) or constellation shaping has been intensively investigated because it off ers ultimate shaping gain of 1.53dB and enables to reach the Shannon limit in additive white Gaussian noise channel. PS modifi es the probability of the amplitude points on the QAM constellation into approximately Gaussian distribution, thus the lower power points are generated more often than the points with a higher power. The amplitude probabilities of PS-256QAM and uniformly-shaped (US) 64QAM signals and is the generalized mutual information (GMI) which represents the transmission rate per received symbol in each polarization. Th e GMI of the PS-256QAM exceeded that of the US-64QAM and can realize the close performance with Shannon limit. In order to realize a high SE transmission with a high noise tolerance, the combination of the high-order QAM and the PS technology has attracted much attention. A single channel 82 Gbaud PS-256QAM transmission with SE of 8bit/s/Hz was achieved over 400km by precisely compensating the frequency response of the transceiver. As the highest-order PS-QAM experiments, single channel 3 Gbaud PS-4096QAM with SE of 15.3bit/s/Hz was fi rstly demonstrated over 160km. Th en, 10 wavelength-division-multiplexed (WDM) 3 Gbaud PS-4096QAM transmission with SE of 17.3bit/s/Hz was realized over 50km. In this paper, we review the recent transmission techniques to generate the signal applied with the high-order QAM and the PS. Th en the numerical performance comparison between PS and US constellations in terms of phase noise is presented. We also describe the experimental results of 80 Gbaud PS-256QAM transmission with precise calibration technique as the transmission with the large capacity and 3 Gbaud PS-4096QAM transmission with OPLL as the transmission employing largest constellations. Th e SE of each transmission was 8 and 15.3bit/s/Hz, respectively. Lastly, we discuss the challenges to further increase the SE.