Day :
- Photonics
Location: July 28, 2016- Embassy I+II
Chair
Bruno Bêche
Université de Rennes, France
Co-Chair
Michael Giersig
Helmholtz-Zentrum Berlin, Germany
Session Introduction
Guangwen Huo
Xijing University, China
Title: A generalized method for calculating phase matching conditions in biaxial crystals
Time : 10:35-10:55
Biography:
Guangwen Huo has completed his PhD degree (Master–Doctor combined program) from the Xi’an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences in 2014. He is now a Lecturer working at the College of Control Engineering, Xijing University. He has published more than 10 papers on nonlinear crystals in reputed journals. His main works include quantum optics, quantum calculating and quantum information.
Abstract:
We present a generalized method for calculating phase matching conditions in biaxial crystals, especially in nonlinear monoclinic and triclinic crystals. Exploiting the angle definition introduced by Japanese mathematician Kodaira Kunihiko, we deduce the angular relations in geometry and obtain the expressions of refractive indices depending on angular orientation of wave vector k and optical axis angle. Then we calculate the phase matching parameters with bismuth borate BiB3O6 (BIBO) crystal in spontaneous parametric down conversion (SPDC) process for the type I and type II. On its basis, we discuss the angular gradients of the pump and emission wave refractive index near the exact phase matching direction, and compare the SPDC with double frequency process in geometrical relations of the refractive index ellipsoids. It indicates the anisotropic structures of nonlinear crystals making a capability of filtering effect, and the nonzero linear mismatch described by refractive index angular gradients can be used to estimate the beam width in crystal. This method is convenient to calculate the phase matching parameters in orthorhombic crystals without solving the quadratic Fresnel equations.
Michael Giersig
Helmholtz-Zentrum Berlin, Germany
Title: Electromagnetic waves interaction with various metallic nanomaterials
Time : 10:55-11:15
Biography:
Michael Giersig has published over 258 internationally refereed publications covering physics, chemistry, materials science, biochemistry, medicine, nanotechnology and engineering. His work has been cited 18051 times quoted in the ISI Index (without self-citations) at an average of over 714 citations per publication, while his H-index is currently 71. He is listed in position 75 in chemistry and 83 in material science in the World Ranking by Thomson Reuters of the 100 Top Chemists and Material Scientists of the past decade 2000-2010.
Abstract:
In this lecture, we will discuss our recent study about the plasmoelectric effect where optical energy can be converted into electrical potential differences in the absence of semiconductors. The active interactions have been visualized by illumination of various in size and morphologies of periodic perforated metallic films by monochromatic light. The nanostructure films have been created by nanosphere lithography (NSL) in conjunction with plasma etching and physical vapor deposition methods. The metallic nanostructures can effectively confine the radiation to nanoscale in the proximity of plasmon resonance whereby the position of this resonance is controlled by the morphology (size and shape) of the nanostructures. The surface potential measurement resulting in enhancement of local fields was analyzed by using Kelvin probe force microscopy (KPFM) under simultaneous illumination in the energy range of the plasmon resonance peak of our nanomaterials towards observing plasmoelectric effects. The recent observation of an enhanced photon induced voltage on Au grating and the second harmonic generation suggests that the overall shape of the structures plays a significant role in determining nonlinear response.
Vladimir B Karalnik
Troitsk Institute for Innovation and Fusion Research (SRC RF TRINITI), Russia
Title: Ultrahigh charging of small spherical grains by the beam-plasma method for creating a compact neutron source
Time : 11:15-11:35
Biography:
Vladimir B Karalnik was graduated from Moscow Institute of Physics and Technology, USSR, in 1990. He received the PhD degree in Physics and Mathematics in 2008 from SRC RF TRINITI. He is currently a Leading Research Scientist with SRC RF TRINITI. His research interests include gas discharge physics and numerical calculations of non-equilibrium plasma interacting with gaseous, liquid and solid objects. He has published more than 90 papers in reputed journals.
Abstract:
Generation of high-voltage high-current electron beams in a low-pressure (0.1-1 Torr) gas discharge is studied experimentally as a function of the discharge voltage and the sort and pressure of the plasma forming gas. The density of the plasma formed by a high-current electron beam is measured. Experiments on ultrahigh charging of micro-particles exposed to a pulsed electron beam with an energy of up to 25keV, an electron current density of higher than 1 A/cm2, a pulse duration of up to 1μs, and a repetition rate of up to 1 kHz are described. Spatial evolution of an electron beam in the course of its propagation towards the target is investigated. A numerical model of ultrahigh charging of grains with a radius of 250μm exposed to a high-energy electron beam is developed. The formation of high-energy positive ions in the electric field around of spherical targets is calculated. The calculations performed for a pulse-periodic mode demonstrate the possibility of achieving neutron yields about 109s–1 in the case of 103 spherical grains.
Kevin Dupraz
Centre national de la recherche scientifique, France
Title: The ABCD matrix for parabolic reflectors and its application to astigmatism free four-mirror cavities
Time : 11:35-11:55
Biography:
Kevin Dupraz has completed his PhD a year ago from University of Paris-Sud in Orsay, France. He works presently on the design of the Laser Beam Circulator of the ELI-NP gamma beam source and on the X-ray characterization of the X-ray line of the ThomX machine. He is Research Associate in a dynamic team focusing on the laser-electron interaction.
Abstract:
Recent researches have demonstrated the possibility to use resonant cavity in a novel mode named burst mode. This mode is a mean to increase the laser peak power staked in the cavity. High peak power has also been obtained by increasing the incident average power. Consequently the staked power in resonant cavity can now reach the damage threshold of the mirrors. This limitation can be overcome by means of large beam mode-size on the optics. On the other hand a larger beam mode-size usually induces a larger astigmatism for folded cavities composed of spherical mirrors. In order to enlarge the spot size and maintain low astigmatism, an optical cavity composed of aspherical mirrors can be considered. The most common and easiest to produce is parabolic mirrors. The main drawback of this type of mirror is alignment issues. Moreover in aim to design the cavity geometry and check the beam mode-size there is no ABCD matrix for parabolic reflectors derived for any incident angles. I will describe how to derive this ABCD matrix by mean of basic considerations and using formalism from quantum billiard. This derivation method is general and can also be used for other aspherical shapes. Then a numerical study of four-mirror cavities composed of two flat and two parabolic mirrors will be described. I will show that this cavity satisfies all constraints related to laser beam injection efficiency, optical stability, cavity-mode, beam-waist size and high stacking power to be a reliable resonant cavity. Finally a dedicated alignment procedure leading to stigmatic cavity-modes is presented to overcome issues related to the optical alignment of parabolic reflectors.
Bruno Bêche
Université de Rennes, France
Title: Soft matter for integrated photonics and resonances: Various hybrid approaches and adaptive technologies
Time : 11:55-12:15
Biography:
Bruno Bêche is Professor of Physics at the University of Rennes 1 (IPR CNRS 6251). His teaching activity took place in several universities as well as in engineering schools in France, holding lectures in fundamental physics, physics of materials, and also photonics at all student levels of education. His research career started on the development of optical components based on lithium niobate as non-linear optical devices and then he worked in the development of III-V semiconductors as components for the wavelength division, multiplexing and lasers (FEMTO-ST and LAAS CNRS, France and NTT Corporation, Japan). At the University of Rennes 1, he started a new field of research, working since a few years in the development of various micro-resonators based on hybrid technologies which combine the use of polymers and plasma treatments, soft matter with fluidic and biology concepts. His research work covers both the theoretical description of the physical aspects of these photonic devices and also the technologies, the characterization and their applications as integrated biosensors in metrology. He is Honorary Member of the 'Institut Universitaire de France' - IUF Paris.
Abstract:
Integrated photonics is increasingly used in sensors and metrology applications. Moreover, the ability to develop new photonic devices through simple, low cost and mass production fabrication steps based on new materials and hybrid approaches is substantial. We will give an overview of targeted current research on integrated photonics based on various hybrid technologies so as to develop multiple families of resonant integrated structures called resonators shaped in 2D or 3D. Such devices devoted to optical resonances and sensors applications and their solving approach highlight the interest to develop specific hybrid processes such as nano-biomolecular film deposition as lipids, self-assembled and micro-fluidic devices, plasma treatments coupled with micro-technology thin layers processes using deep UV lithography and so on.
Mikhail Kaliteevski
ITMO University, Russia
Title: Quantization of electromagnetic field in an inhomogeneous medium based on scattering matrix formalism (S-quantization)
Time : 12:15-12:35
Biography:
Mikhail Kaliteevski has completed his PhD from Ioffe Institute, St-Petersburg, (Russia). He is principal research scientist and head of research team focusing on nanophotonics in Academic University, Ioffe Institute and ITMO University. He has published more than 150 papers in reputed journals and serving as an Editorial Board Member of repute.
Abstract:
We have developed a procedure for quantization of the electromagnetic field in a layered inhomogeneous media based on analysis of the Eigen values of the scattering matrix (S-matrix). In contrast to the method involving quantization of the electromagnetic field, involving the use of periodic boundary conditions (Born–von Karman conditions), the proposed procedure (S-quantization) is based on equality of the amplitudes of waves incident on a quantization box and waves outgoing from the quantization box, which is equivalent to equating unity Eigen values of the scattering matrix. We perform a comparison of the density of states and spatial structure of the field calculated with periodic boundary conditions and using the procedure of S-quantization. S-quantization allows calculating modification of the spontaneous emission rate for arbitrary inhomogeneous structure and direction of the emitted radiation. S-quantization solves the long-standing problem coupled to normalization of the quasi-stationary electromagnetic modes. Examples of application of S-quantization for the calculation of spontaneous emission rate for the cases of Bragg reflectors, micro-cavities, photonic quasi-crystals and plasmonic structures are demonstrated.
- Types of Lasers | Lasers in Industry
Location: July 28,2016- Embassy I+II
Chair
Stephan Bruening
Schepers GmbH & Co. KG, Germany
Co-Chair
Belkacem Meziane
Université d’Artois, France
Session Introduction
Bernhard Roth
Leibniz University Hannover, Germany
Title: All-polymer planar optical sensing devices integrated in thin foils
Time : 12:35-12:55
Biography:
Bernhard Roth obtained his PhD in 2001 at University Bielefeld. From 2002-2007, he served as Group Leader at University Duesseldorf and obtained his Habilitation in Quantum Optics in 2007. From 2007-2010, he worked as Associate Professor at University Duesseldorf and from 2011-2012 as Managing Director at the research centre innoFSPEC, University Potsdam and Leibniz Institute for Astrophysics Potsdam. Since 2012, he is Director of the Hannover Centre for Optical Technologies and since 2014 serving as Professor at the University Hannover. His scientific activities include research in laser development and spectroscopy, polymer optical sensing and optical technology for illumination, information technology and the life sciences.
Abstract:
Planar optical sensor devices integrated into thin polymer foils hold great promise for a wide range of new applications in structural health monitoring for buildings and aircraft or process control in production environments and the life sciences. Various such applications demand for fully integrated, large area optical foils with extensive optical sensor functionality. Therefore, the primary challenge is to develop sensor concepts which translate the physical and chemical parameters into optical signals, such that the resulting sensor networks will allow large-area, spatially-resolved measurements, and to manufacture and integrate all components required, e.g. laser sources, detectors, optical waveguides and coupling elements into thin foils, ideally using high-volume, roll-to-roll manufacturing technology. Consequently, research in the field has been very active during the last few years and, besides the investigation of suitable optical sensor concepts, revolves about the development of novel production technologies, often through combination of modern laser technology and state-of-the-art micro-structuring, as well as concepts for large-area integration. In my talk, I will give an overview on our research in this field. Our activities range from the realization of efficient optical waveguides and coupling elements using laser and hot embossing techniques, the development, simulation and demonstration of all-polymer optical sensor devices for detection of, e.g., strain, humidity, or concentration to combination of such systems to more complex arrays intended for distributed 2D sensing. I will present some of the results we recently obtained and discuss the next steps of our work as well as the route towards resource and cost-efficient implementation.
Stephan Bruening
Schepers GmbH & Co. KG, Germany
Title: Embossing dies for surface functionalization by laser micro structuring
Time : 12:55-13:15
Biography:
Stephan Bruening is Member of the Executive Board of Schepers and responsible for R&D projects and security customer projects. He graduated in Münster and Hagen, holds an MSc degree in Photonics. During his PhD studies at the RWTH-Aachen, he worked in the area 3D-micro-structuring of metallic surfaces. In 2012, he was the winner of the Innovation Award Laser Technology of the AKL and ELI. Beside the continuous further development of the DIGILAS micro processing equipment, for e.g. intaglio printing, micro embossing, he is the R&D Manager for publicly funded projects by the BMBF, such as MICROPHOT, PIKOFLAT and currently MULTISURF.
Abstract:
The functionalization of surfaces and layers is a key technology of the 21st century. It is paving the way for the transformation of photonics into highly integrated components. In this way, traditional materials get new or improved features and new materials are developed for a resource-efficient industrial use and an increased efficiency. Virtually any structure can be written in a direct manner by only one correspondingly precise control of the laser beam. This approach is particularly well-suited to produce a so-called master which can then be used for the parallel mass reproduction of the structure, as for example for embossing plates or rollers. This second duplication step is an established process, as a disadvantage of direct laser writing is its genuine serial character, i.e., the focused laser beam is sequentially moved over all those regions of a surface where material should be removed. Embossing dies processed by ultra-short pulsed lasers are already used in some fields to transfer microstructures directly into a metal surface. One major advantage of micro structuring by ultra-short pulsed lasers is the melt-free ablation of steel surfaces of three dimensional micro structures within one step. The combination of ultra-short pulsed laser and high-precision machinery and the handling of high resolution digital file formats has been realized in the cylinder micro processing system DIGILAS for embossing dies. This contribution shows state-of-the-art structures and future possibilities of this new technology.
Jing Bai
University of Minnesota Duluth, USA
Title: Investigation on soliton related effects in mid-infrared quantum-cascade lasers
Time : 13:55-14:15
Biography:
Jing Bai is an Associate Professor and the Director of Graduate Studies (DGS) in Department of Electrical Engineering at University of Minnesota Duluth (UMD). She received her PhD degree in Electrical and Computer Engineering at Georgia Institute of Technology in 2007. His current research activities focus on nano-photonics, nano-photovoltaics, non-linear optics and nanoscale biomedical devices. Her research at UMD has been supported by the National Science Foundation (NSF), the Whiteside Institute for Clinical Research, the MN Drive Initiatives, and the Graduate School of University of Minnesota.
Abstract:
Since the first demonstration in 1994, quantum-cascade lasers (QCLs) have become one of the most important solid-state mid-infrared (MIR) coherent light sources for various applications in environment sensing, medical diagnosis and defense and free-space communication. Dynamics analysis and stable pulse progression of MIR QCLs are crucial in order for QCLs to have reliable performance in these applications. An explicit description of dynamics of QCLs is inevitably complicated when compared to conventional lasers because of the unique combination of ultrafast carrier scatterings and gain recovery, significant non-linearities and dispersion effect in a QCL medium. Discussions on dynamics in MIR QCLs have been mostly focused on the stability analysis. However, the interplay between the non-linearity and dispersion effect during the QCL coherent pulse progression has received less attention. Especially, in a nonlinear dispersive lasing medium, the combination of group-velocity dispersion (GVD) and self-phase modulation (SPM) could possibly lead to the soliton formation. A measurement of GVD in the MIR QCLs has been reported. The interaction between the GVD and the saturable absorber (SA) in the self-induced transparency (SIT) modelocking of QCLs is discussed, where the analysis is based on the evolution of electric field only and the coherence effect in the lasing transition is not included. In our current study toward the soliton formation in QCLs, we got the opportunity to carefully examine each of those two effects and analyze their interaction on the coherent pulse progression in both time-domain and frequency-domain.
Maria Chernysheva
Aston University, UK
Title: Advances in mid-infrared mode-locked fiber lasers
Time : 14:15-14:35
Biography:
Maria Chernysheva has completed her PhD from Fiber Optics Research Center of the Russian Academy of Science in 2014. Currently, she is the Marie Sklodowska-Curie Fellow at Aston University. She has an internationally recognized track record of 13 publications in high-impact factor peer review journals in the fields of rare-earth-doped mode-locked fiber lasers. The area of her research expertise include development of mode-locked lasers and pulse amplifiers; analysis of advanced saturable absorbers and their implementation; numerical modeling of higher-order soliton; dispersion managed soliton pules in passive silica and special fibers.
Abstract:
Mid-infrared light sources have become an object for wide research and industrial interest since early 2000, due to numerous of practical applications: greenhouse gases and pollutants monitoring to help climate change mitigation, high precision optical frequency standards for spectroscopy, global positioning systems (GPS) and optical clocks, LIDAR systems, and novel diagnostic techniques in medicine. All-fiber femto-second laser configuration is beneficial, since the laser fabrication process is straight forward, does not require “clean room” facilities and photolithography, and decreases the cost metric and power consumption. In my review I will start with silica Thulium and Holmium doped fiber lasers, demonstrating both ultrashort pulse durations and high output power the 1.8-2.1 μm wavelength range. However, the exceptional performance of fiber lasers cannot be extended far beyond the 2.5 μm wavelength, owing to the rapid decrease of emission intensity due to high losses in silica fibers. The fiber laser generation around 3 μm was enabled with the availability of high-purity fluoride, chalcogenide and ZBLAN glass fibers. I will review the application of these special glass matrixes to support generation at 2.75 μm in Erbium-doped fibers and at 2.85 μm in Holmium and Prazeodinium -doped optical fibers. In 2002, M.C. Downer presented pioneer work on gas-filled hollow-core fibers and announced “a new era in the nonlinear optics of gases”. Different gasses, such as acetylene and HCN, can provide gain at Mid-infrared wavelengths at low vapor pressure when pumped with nanosecond pulses. Finally I will analyze the saturable absorbers suitable for operation in Mid-infrared wavelength region.
Baldemar Ibarra-Escamilla
Instituto Nacional de AstrofÃsica, Mexico
Title: Single and dual wavelength Er:Yb double clad fiber lasers
Time : 14:35-14:55
Biography:
Baldemar Ibarra-Escamilla received the Bachelor’s degree in Electronics from the BUAP in Puebla, Mexico, in 1994. He received the MS and PhD degrees in Optics from the InstitutoNacional de Astrofísica, Optica y Electrónica (INAOE), Mexico, in 1996 and 1999, respectively. He did a Post-doctoral stay and a Sabbatical year at the Electro-Optics Graduate Program, University of Dayton, USA during 2000 and from July/2008-July/2009, respectively. He is currently a Researcher of the Optics Department at INAOE. His interests are in modelocked fiber lasers, fiber amplifiers, tunable fiber lasers, fiber sensors, high power fiber lasers and fiber optics nonlinear effects.
Abstract:
Actively Q-switched fiber lasers have been investigated due their applications in remote sensing, medicine, and terahertz generation. This technique is usually achieved to improve pulses stability and higher pulse energies. Several active Q-switched fiber laser configurations based in the use of free-space, all-fiber or fiber pigtail acousto-optic have been reported. Moreover, double-clad fibers (DCFs) are attractive as gain medium due their high conversion energy feature. Recently, we have reported an Er/Yb DCF tunable laser in continuous wave (cw) and actively Q- switched fiber laser using a fiber Bragg grating (FBG) as wavelength selective in a linear cavity resonator. The minimum pulse durations were obtained with 420 ns at a repetition rate of 120 kHz and ~0.7 W average output power in cw and 1.03 W average output power in pulsed mode. Also, we reported an actively Q-switched dual-wavelength fiber laser using an Er/Yb DCF in a linear cavity limited by a pair of FBGs in one side, and a Sagnac interferometer in the other side. We also have reported a tunable dual-wavelength actively Q-switched Er/Yb DCF laser using a polarization maintaining FBG for both generated laser wavelengths tuning. In other configuration, we reported a ring cavity dual- wavelength fiber laser with an Er/Yb DCF. By mechanical compression/stretch applied on the FBGs the laser generated wavelength maximal separation was ~4 nm. In this work, we present a review of our previous work in the area of single and dual fiber lasers.
O Pottiez
Centro de Investigaciones en Óptica, Mexico
Title: Noise-like pulse dynamics in passively mode-locked fiber lasers
Time : 14:55-15:15
Biography:
O Pottiez received his PhD from FacultéPolytechnique de Mons (Mons, Belgium) in 2001. His research interests include mode-locked fiber lasers for ultrashort pulse generation, as well as the study of non-stationary dynamics of these sources, in particular noise-like pulsing and optical rogue wave generation. He has authored or coauthored 75 publications in peer-reviewed journals and 100 international conference proceedings.
Abstract:
Due to their unique properties, noise-like pulses (NLPs) are currently attracting increasing interest for both fundamental research and applications. NLPs are chaotic bunches of optical pulses whose formation corresponds to a not-so-stable mode of operation of passively mode-locked fiber lasers. Due to their extremely complex fine structure dynamics, NLPs constitute an ideal benchmark for the study of extreme events known as optical rogue waves. On the other hand, their high pulse energy, wide bandwidth and short coherence time makes them attractive for applications including nonlinear frequency conversion, supercontinuum generation, materials processing and sensing. However, their puzzling dynamics and the difficulty to characterize them precisely make their study extremely challenging. During this talk we will present some recent advances of our group in the study of NLP generation in the 1500 nm region. Different fiber laser architectures will be considered. Record single pulse energies of 0.3 ïJ (~1000 times the energy of a conservative soliton) and spectral bandwidths of several hundreds of nm (~10 times the doped fiber bandwidth) are reported. Besides, using an original measurement technique, we retrieve information on the intimate inner structure of NLPs and confirm their connection with optical rogue waves. We also report the observation of a series of very intriguing NLP dynamics which bears some analogy with the soliton rain dynamics.
Belkacem Meziane
Université d’Artois, France
Title: Predicting the unpredictable with an isomorphic single-control parameter structure of the Laser-Lorenz equations
Time : 15:15-15:35
Biography:
Belkacem Meziane received the MS degree in Electrical Engineering (1978) from the Florida Institute of Technology, Melbourne, USA, the PhD degree (1992) and the “Habilitation à Diriger des Recherches” (1996) from ENSSAT, Université de Rennes I, Lannion, France. From 1979 to 1990, he was a Lecturer at the Algiers-University Physics Department (USTHB), Algeria. From 1990 to 1998, he was a member of the Optronics Division at ENSSAT. In 1999, he’s been a tenured Professor at the Faculty of Sciences, Université d’Artois, Lens, France. He is the author of over 30 published papers, including 2 book chapters on laser dynamics
Abstract:
Leaning on the extraction of, so far unidentified, recurrent-properties, we put forward an isomorphic structure that converts the Laser-Lorenz equations, whose dynamic solutions are usually described in terms of three independent factors, into a single control-parameter system. Such an isomorphism is shown to bring an intrinsic simplification that offers much better depictions of the Laser non-linear dynamics, while it allows for quicker and forthright inspection of the control-parameter domains, inside which well-defined periodic, symmetric and asymmetric, as well as chaotic solutions occur. The single control-parameter equations will be demonstrated to contain the full nonlinear dynamics of the original set. Functional graphical-representations, with respect to this lone control-parameter, will be shown to depict the complete hierarchy of typical windows, each bearing specific solutions. The objectives of the presentation are threefold. The primary one is to demonstrate, for the first time, that the solutions of the single mode Laser equations possess some repeatedly organized and systematic properties that allow for straightforward identification of its periodic windows, asymmetric and chaotic solutions, following some judicious arrangements of its control-parameters. Based on such endorsement, a second step will naturally end-result to transforming the equations into a single control-parameter set which encloses the same abundant dynamical solutions while preserving the full hierarchies and features of the three-control-parameter system. As a final concern, a summarizing generic map will sum up the predicted solution-windows associated with the single control-parameter variable. Hopefully, such a noteworthy simplification will render non-linear Laser dynamics much easier to apprehend.
Guofei An
Southwest Institute of Technical Physics, China
Title: Optimization of a DPAL system by adjusting cell structural parameters and cell temperatures
Time : 15:35-15:55
Biography:
Guofei An received his Bachelor’s degree in Applied Physics at Northwest Polytechnical University and has completed his PhD in Condensed Matter Physics from Northwest Polytechnical University in China at 2014. After obtaining his PhD, he worked as a research fellow of Laser Engineering in the Southwest Institute of Technical Physics. His scientific interests are in the area of laser kinetics, quantum electronics, nano-laser, and heat transfer in laser cavity. He has published more than 30 papers in scientific journals since 2010. Currently, he is mainly engaged in the research on the diode-pumped alkali vapor laser including both theoretical modeling and experiment.
Abstract:
In recent years, a diode-pumped alkali laser (DPAL) has provided the significant promise for high-powered applications. A series of models have been established to analyze the DPAL’s kinetic process and most of them were based on the algorithms in which only the ideal 3-level system was considered. However, alkalis are the most easily ionized atomic species, especially for Rb and Cs. under the condition of strong pumping the electrons will be excited to the higher levels, 62D5/2,3/2 and 82S1/2, by energy pooling collisions. Then, further ionization processes including photo-ionization and Penning ionization will occur on the 62D5/2,3/2 and 82S1/2 levels resulting in decrease of the density of neutral atoms. To examine the kinetic processes of the gas-state media, a mathematical model is developed taking into account the process of normal transition, energy pooling, and ionization. The procedures of heat transfer and laser kinetics were combined together in our theoretical model. We systemically investigated the influences of the temperature, cell length, and cell radius on the output features of a DPAL. By optimizing these key factors, the optical-to-optical conversion efficiency of a DPAL can be evidently improved. Further, the calculated results indicate that the influence of energy pooling and ionization can be obviously suppressed with the optimal parameters. In the case of high pump power, 1000 W, the influence of energy pooling and ionization on output power decreases from 6.02% to 1.04% and the optical-to-optical efficiency increases from 16.5% to 51.5% after optimizing. Basically, some conclusions we obtained here can be extended to any other kinds of end-pumped laser configurations.
- Workshop
Location: July 28, 2016- Embassy I+II
Chair
Sergei A Kozlov
ITMO University, Russia
Co-Chair
Sergey A Moiseev
Kazan National Research Technical University, Russia
Session Introduction
Aleksey Mickhailovich Polubotko
Saint Petersburg State University, Russia
Title: Strong quadrupole light-molecule interaction and surface-enhanced optical processes
Time : WS01
Biography:
Aleksey Mickhailovich Polubotko graduated from Physical Faculty of Leningrad State University in 1973. He completed his PhD in A F Ioffe PhysiÑo-Technical Institute Russian Academy of Sciences and defended the PhD thesis in Azerbaijan Institute of Physics in Baku in 1983. Currently, he works as a Physicist Theorist and a Senior Scientific Researcher of the sector of Semi-conductors and Dielectrics of the Department of Dielectrics and Semiconductors of A F Ioffe Physico-Technical Institute in Saint Petersburg. He has more than 120 scientific papers, preprints and abstracts published in reputed journals and reported in many scientific conferences.
Abstract:
Surface-Enhanced Optical Processes, SERS, SEHRS and SEIRA are of great interest for physics, chemistry and biology since they all allow increasing strongly the sensitivity of these spectroscopic methods and there is a fundamental physical mechanism, which causes the enhancement in these processes. It is so-called strong quadrupole light-molecule interaction, arising in surface electromagnetic fields, strongly varying in space near a rough metal surface. Just this interaction is responsible for the enhancement in SERS 106, in SEIRA 103 -104 and in SEHRS 1012 and significantly higher. Moreover, this interaction is the base for implementation of Single Molecule Detection by SERS, when the enhancement can achieve the value 1014 -1015. This interaction is responsible for appearance of forbidden lines in all these processes on molecules with sufficiently high symmetry. Indeed, these strong lines were observed in ethylene and diprotonated in SEIRA and in pyrazine and phenazine in SEHRS. They are the lines, caused by vibrations with the unit irreducible representation of a molecule symmetry group. Such strong lines are observed in SERS as well. However, they are caused by vibrations with the irreducible representations, which describe transformational properties of the dipole moment component , which is perpendicular to the metal surface. At present the theory of the above mentioned processes, based on this concept is created and explains the most of the observed phenomena, accompanying SERS, SEHRS and SEIRA.
Sergei A Kozlov
ITMO University, Russia
Title: Polarization-independent subcarrier quantum communication system and its application in ITMO University quantum network
Time : WS02
Biography:
TBA
Abstract:
A quantum key distribution system based on the subcarrier wave modulation method has been demonstrated which employs the BB84 protocol with a strong reference to generate secure bits at a rate of 16.5 kbit/s with an error of 0.5% over an optical channel of 10 dB loss, and 18 bits/s with an error of 0.75% over 25 dB of channel loss. To the best of our knowledge, these results represent the highest channel loss reported for secure quantum key distribution using the subcarrier wave approach. A passive unidirectional scheme has been used to compensate for the polarization dependence of the phase modulators in the receiver module, which resulted in a high visibility of 98.8%. The system is thus fully insensitive to polarization fluctuations and robust to environmental changes, making the approach promising for use in optical telecommunication networks. Further improvements in secure key rate and transmission distance can be achieved by implementing the decoy states protocol or by optimizing the mean photon number used in line with experimental parameters. The system was used in deployment of ITMO University quantum network in Saint Petersburg, Russia, where a polarization independent subcarrier wave quantum key distribution operation with sifted bitrate 250 kbit/s was for the first time demonstrated in metropolitan telecommunication network channel composed of standard SMF-28e fibers with 1.5 dB loss.
Aleksey Mickhailovich Polubotko
Kazan National Research Technical University, Russia
Title: Electrodynamical forbiddance of the strong quadrupole light-molecule interaction and its manifestation in fullerene C60
Time : WS03
Biography:
Aleksey Mickhailovich Polubotko graduated from Physical faculty of Leningrad State University in 1973. He completed his PhD in A.F. Ioffe PhysiÑo-Technical Institute Russian Academy of Sciences and defended the PhD thesis in Azerbaijan Institute of Physics in Baku in 1983. Currently, he works as a physicist theorist and a senior scientific researcher of the sector of semi-conductors and Dielectrics of the Department of Dielectrics and Semiconductors of A F Ioffe Physico-Technical Institute in Saint Petersburg. He has more than 120 scientific papers, preprints and abstracts published in reputed journals and reported on many scientific conferences.
Abstract:
At present it is well proved in our works that the reason of SERS, SEHRS and SEIRA is so-called strong quadrupole light-molecule interaction, which arises in surface electromagnetic fields strongly varying in space near a rough metal surface. This interaction is associated with terms of the light-molecule interaction Hamiltonian with the quadrupole moments and , or their linear combinations transforming after the unit irreducible representation of the molecule symmetry group, which results in appearance of strong forbidden lines in molecules with sufficiently high symmetry. The general requirement for observation of these lines is belonging of the molecule to the symmetry group, where the component of the dipole moment , which is perpendicular to the surface transforms after the irreducible representation another, than the unit one. However, it appears that for the molecules, which belong to the cubic symmetry groups and the icosahedral groups and the strong quadruple light-molecule interaction, is forbidden due to specificity of these groups and the electrodynamic law. Therefore, the light-molecule interaction in these molecules is of a purely dipole type. This property must result in the absence of the lines with the unit irreducible representation in the SEIRA and SEHRS spectra of molecules, belonging to these groups. The absence of the indicated lines at 496 and 1470 was observed in fullerene that strongly supports the Dipole-Quadrupole theory of the indicated processes.
Artur V. Gleim
ITMO University, Russia
Title: Polarization-independent subcarrier quantum communication system and its application in ITMO University quantum network
Time : WS04
Biography:
TBA
Abstract:
A quantum key distribution system based on the subcarrier wave modulation method has been demonstrated which employs the BB84 protocol with a strong reference to generate secure bits at a rate of 16.5 kbit/s with an error of 0.5% over an optical channel of 10 dB loss, and 18 bits/s with an error of 0.75% over 25 dB of channel loss. To the best of our knowledge, these results represent the highest channel loss reported for secure quantum key distribution using the subcarrier wave approach. A passive unidirectional scheme has been used to compensate for the polarization dependence of the phase modulators in the receiver module, which resulted in a high visibility of 98.8%. The system is thus fully insensitive to polarization fluctuations and robust to environmental changes, making the approach promising for use in optical telecommunication networks. Further improvements in secure key rate and transmission distance can be achieved by implementing the decoy states protocol or by optimizing the mean photon number used in line with experimental parameters. The system was used in deployment of ITMO University quantum network in Saint Petersburg, Russia, where a polarization independent subcarrier wave quantum key distribution operation with sifted bitrate 250 kbit/s was for the first time demonstrated in metropolitan telecommunication network channel composed of standard SMF-28e fibers with 1.5 dB loss.
Vladimir Egorov
Saint Petersburg State University, Russia
Title: Maintaining security against photon-number-splitting attacks in subcarrier wave quantum communication systems
Time : WS05
Biography:
Vladimir Egorov has completed his PhD studies in Optics at ITMO University in 2015. He has published more than 15 papers in peer reviewed journals. His research interests include quantum communications and networking, nanophotonics and plasmonics.
Abstract:
Subcarrier wave (SCW) approach to quantum communication systems demonstrates many promising capabilities for establishing multiuser quantum networks. In this type of systems the quantum signal is obtained at spectral sidebands in course of phase modulation of light at the central frequency emitted by the source. All current SCW experiments use laser radiation for generating the light at central frequency, and its subsequent modulation and attenuation for creating the sidebands. Therefore, the photon number statistics in the quantum channel is described by the Poisson distribution, and countermeasures against photon-number-splitting (PNS) attack are in order. Differences in SCW architecture from other types of quantum communication systems require developing special techniques for maintaining security against PNS. For the widely-employed decoy states method, one must ensure that the eavesdropper cannot identify the decoys by monitoring the fluctuations of intensity of light at the central frequency. To solve this problem, we propose a novel experimental scheme of the SCW transmitter module. The “strong reference” protocol especially proposed as an alternative to the decoy method in SCW, establishes certain bounds on the filtering subsystem in the receiver module. We calculate the optimal parameters of the source, detector and filter in the system in order to find an effective trade-off between them. Finally, we developed a novel method of maintaining security against PNS by analyzing the counting statistics using a photon-number-resolving detector. We compare the system architectures from engineering point of view and calculate key generation rates for these protocols, defining optimal solutions for different channel losses.
E N Kotlikov
Saint Petersburg State University of Aerospace Instrumentation, Russia
Title: Method for determining of the optical constants for films and materials inside the absorption bands region
Time : WS06
Biography:
TBA
Abstract:
Spectrophotometric methods are most commonly used for determining of the optical constants of films and materials are. These methods are based on measuring of the reflection R (λ), transmission T (λ) and absorption A (ï¬ï€©ï€ spectra and make it possible to obtain the dispersion characteristics of the optical constants throughout the required range of the spectrum. The principal difficulties arise at the stage of analysis of the spectra, and obtaining from them the information about optical constants, particularly in the absorption bands regions. In terms of mathematical methods of spectra processing, methods of determining of the optical constants can be divided into two sets: analytical and numerical. The first set involves the search for suitable analytical expressions for the direct calculation of optical constants in various specific cases. The second one is based on numerical methods for finding the minimum of functional of quality. Currently there is no single universal method for determining the optical parameters of of real films and materials from the spectrophotometric data. It is caused by incorrectness and the ambiguity in determining the optical constants from the spectra. We propose a new method based on the correction of measured spectra taking into account the absorption. After this correction, the absorption becomes zero and one variable - the absorption coefficient is excluded from the calculation, which greatly simplifies finding of the optical constants. The main idea of the proposed method is based on the additivity of energy conservation law, which can be presented as 1=T(λ)+R(λ)+A(ï¬ï€©. Absorption may be divided into two parts: A (ï¬ï€©=AT +AR, where AT and AR defines the absorption contribution to the transmission and reflection spectra. To find the AR (ï¬) and AT(ï¬), we use the correction functions fr and ft which define the contribution of total absorption A(ï¬ï€© into AR(ï¬) and AT(ï¬). Correction functions fr and fl are calculated using the approximate absorption spectrum A(ï¬ï€©ï€® Spectra without absorption are defined as: T0(λ)=T(λ)+ftÐ(ï¬ï€©ï€¬ï€ ï€ R0(λ)=R(λ)+ fRÐ(ï¬ï€©ï€¬ where all the values in the right-hand sides are known. It is important to note that the dispersion of the refractive index in the spectra of T0 (λ) and R0 (λ) remains unchanged. The absorption coefficient ï¡ can be found from the spectra by known methods. By this method we have determined the optical constants of the thin films BaF2, Ba0.98Mg0.02F2, CaF2, CaYF5 and various materials of the transmissive optics in the absorption bands region in the middle IR spectral range.
Andrei Gaidash
ITMO University, Russia
Title: Proof of standard security analysis compatibility with a sub-carrier wave quantum communication method
Time : WS07
Biography:
Andrei Gaidash recieved two MS degrees in Photonics and Optical Information Technologies at ITMO University (Russia) and University of Rochester (USA) in 2015. He is currently a first year Post-graduate student at ITMO University. His research interests include quantum information and communication technologies.
Abstract:
The field of quantum communication and key distribution (QKD) is reaching its maturity, opening the door to commercially available systems and quantum networks. For secure optical networking applications, the sub-carrier wave (SCW) QKD systems demonstrate some important advantages, in particular high spectral efficiency, polarization independence, and unidirectionality. However, currently there is no strict proof of security presented for this class of QKD systems due to an uncommon way of generating the quantum signal in them. In SCW systems, phase modulation of a high-intensity signal produces the quantum signal at its spectral sidebands. We investigate the properties of quantum signals in a SCW system using the theory of electro-optical modulators in order to prove that the standard security analysis can be applied. We consider both classical and two quantum approaches: with finite and infinite number of interacting modes. We discuss how to estimate the number of interacting modes and how a finite number of them affects on the modulation process. Knowing how the quantum states develop due to modulation, we derive an equation for quantum interpretation of the second order correlation function for both sidebands. We then demonstrate that the second order correlation function equals unity, and thus both sidebands can be interpreted as one coherent state with double mean photon number compared to one sideband. Therefore, we for the first time demonstrate that the quantum channel in the SCW system satisfies the conditions of the standard (for example, Inamori-Lutkenhaus-Mayers or Gottesman-Lo-Lutkenhaus-Preskill) security analysis for QKD with coherent states source.
Kozubov Anton
ITMO University, Russia
Title: Linear optical quantum circuits construction algorithm based on directed graphs or transform matrices
Time : WS08
Biography:
Anton Kozubov has received his Bachelor’s degree at the ITMO University in 2015 and is at present in his first year of Master’s program. He works as an engineer in quantum information laboratory at ITMO University. His scientific areas of interest include quantum computing and communications.
Abstract:
Today great interest in quantum information is observed throughout the world. Quantum computing schemes based on quantum algorithms will allow for effectively solving many complicated mathematical problems. There are two different approaches to implementing the experimental schemes for quantum algorithms: based on linear (LOQC) or quantum circuits with nonlinear elements. The LOQC schemes are easier to implement, but their mayor disadvantage lies in probabilistic nature of their functioning. The probabilistic nature of obtaining results in the LOQC supports the relevance of the search of the most effective variants of optical circuit designs for specific quantum operations: their composition and arrangement of the basic quantum computing elements. In this report we propose an algorithm for automatically constructing LOQCs from several basic elements. The program uses the transformation matrix, relating the input and output parameters of the quantum system, or a directed graph that describes the composition of the desired circuit. The algorithm is based on the method of dual-rail encoding. In our implementation, beam splitters and wave plates are used as the basic elements. These basic elements are required for optical realization of any one- or two-qubit gates. As a result of this work, we developed an algorithm that allows implementing LOQC using the transformation matrix between the input and output states, or a directed graph. Additionally, the programs allow analyzing the circuit relative error probability, and choose the best possible realization.
Dmitrii Pankin
St. Petersburg State University, Russia
Title: Investigation of process of quartz glass crystallization by confocal Raman spectroscopy
Time : WS09
Biography:
Dmitrii Pankin has completed his Master's thesis. Currently, he is a PhD student at Saint Petersburg State University on physical faculty.
Abstract:
In our work, industrial type glass for UV (KU-1 quartz glass (QG)), visible (KV QG) and IR (KI QG) regions have been choosed. Sizes of samples are 40x40x5 mm. It’s working surface had been polished by CeO2 and after that heating was performed. In region 1100-1300°C stability of temperature was maintained at ± 2°Ð¡. Heating was conducted during 10 hours. Visual observations of working surface has shown growth of crystallization regions (CRs) with typical in-plane dimensions of tens of microns. Nevertheless indepth dimension can reach about 100 microns. Shapes of CRs varies with type and concentration of impurities that are present in the type of glass. Most different shapes of CRs were observed in KV because of high concentration of impurities and OH bonds comparing to that in other samples. Mostly shapes of CRs in other samples has radial symmetry. It was due to begin of crystallization near impurity metal ion such as Al3+, Ca2+, Na+, Mg2+, Mn2+ or Fe2+. This ions substitute Si4+ in SiO2 tetrahedra or embedded between them. Investigation of early stages crystallization in industrial type quartz were performed by confocal Raman spectroscopy techniques. By 2D mapping and in-depth confocal measurement it was shown that crystalline region is made up of crystallization center, intermediate layer and thin bound. Intermediate layer is made up of α-SiO2 quartz nanoparticles with diameter more than 20 nm. According to Raman spectra and our calculations thin bound is made up of α-SiO2 nanoparticles with diameter 2-8 nm coagulated with Fe2O3, Fe3O4, TiO2 and SiC. Such coagulation enhance multiphonon processes in Raman scattering of crystalline quartz.
- Optoelectronic Materials and Devices| Optical system| Optical networking | Nanophotonics
Location: July 29, 2016- Embassy I+II
Chair
Abdullah J Zakariya
Ministry of Interior Kuwait, Kuwait
Co-Chair
E U Rafailov
Aston University, UK
Session Introduction
Jie Bao
Tsinghua University, China
Title: The quantum dot spectrometer-Exploiting the limitless number of colors of QDs
Time : 09:00-09:20
Biography:
Jie Bao is an Associate Professor in the Electronic Engineering Department of Tsinghua University. Before joining Tsinghua, he graduated with a PhD degree from Brown University and carried out his Post-doc research at MIT. He is a member of the National 1000 Plan Professorship Program in China, and was awarded with ‘10 Emerging Star Scientists in China’ in 2015.
Abstract:
Speaking of quantum dots, the first thing that comes to mind is probably their most distinctive and characteristic property-that their band gaps, thus colors, can be continuously and finely tuned over a wide range. This property gives rise to a large pool of countless number of materials, which all share very similar natures and properties. In this speech, I will talk about how such a unique property is being exploited by the invention of the quantum dot spectrometer, and how we envision a ubiquitous sensing toolbox emerging out from a nano dot.
Abdullah J Zakariya
Ministry of Interior Kuwait, Kuwait
Title: Monolithically integrated tunable QW laser
Time : 09:20-09:40
Biography:
Abdullah J Zakariya has completed his PhD from University of Central Florida. He worked as a Wireless Communications Engineer for 15 years and currently holds the position of the Wireless Networks Director at the Ministry of Interior – Kuwait where he takes up a variety of projects involving wireless public safety networks, telecommunications jammers and MPLS optical fiber networks. He also has several publications in the optics field specifically in tunable lasers and LEDs; moreover, he has several publications in the biomedical optics field focusing on point of care testing and lab-on-a-chip devices.
Abstract:
A monolithically integrated broadly tunable MQW laser that utilizes a combined impurity-free vacancy disordering (IFVD) of quantum wells and optical beam steering techniques is proposed, fabricated and investigated experimentally. The device consists of a beam-steering section and an optical amplifier section fabricated on a GaAs/AlGaAs quantum well (QW) p-i-n heterostructure. The beam steering section forms a reconfigurable optical waveguide that can be moved laterally by applying separately controlled electrical currents to two parallel contact stripes. The active core of the gain section is divided in into selectively intermixed regions. The selective intermixing of the QW in the gain section results in neighboring regions with different optical bandgaps. The wavelength tuning is accomplished by steering the amplified optical beam through the selected region where it experiences a peak in the gain spectrum determined by the degree of intermixing of the QW. The laser wavelength tunes to the peak in the gain spectrum of that region. The IFVD technique relies on silica (SiO2) capped rapid thermal annealing and it has been found that the degree of intermixing of the QW with the barrier material is dependent on the thickness of the SiO2 film. Optical characterizations of the intermixed regions have shown a blue shift of peak of the electroluminescence emission of 5 nm, 16 nm and 33 nm for the uncapped, 100 nm and 200 nm respectively when compared to the as grown sample. The integrated laser exhibited a wavelength tuning range of 17 nm (799 nm to 816 nm).
Shixiang Xu
Shenzhen University, China
Title: Spectrum-polarization encoding for broadband laser pulses basing on rotatory dispersion and its possible applications
Time : 09:40-10:00
Biography:
Shixiang Xu has completed his PhD in 1998 from Shanghai Institute of Optics and Fine Mechanics, China. His current position is a Professor in Shenzhen University. His research interests include ultrashort pulse laser, ultrafast imaging and pulsed terahertz optics. Till now, he has published more than 60 papers in peer-reviewed journals and 15 patents. He also serves as a member of Laser Professional Committee of Chinese Optical Society. Recently, he has been elected to the Council of Guangdong Optical Society of China.
Abstract:
As we know, Chirped Pulse Amplification (CPA), a kind of time-spectrum encoding, has scaled the femto-second pulse to several petawatts. Here we report a novel technology; we call it spectrum-polarization encoding (SPE) for broadband pulse. SPE can originate from the optical rotatory dispersion of some optical active materials, e.g. quartz crystal, and can be compensated by inducing equal value of the rotatory dispersion but with opposite sign. By using Ti:S as a polarization-dependent gain, our calculations show proper SPE allows an amplifier to boost an 800 nm pulse up to mJ level with a bandwidth to support few-cycle pulse duration. Further, M. Kalashnikov claimed that SPE might open a way to produce PW few-cycle laser pulses in a CPA system. We also find SPE may be able to tune output spectrum of a tunable laser with a polarization-dependent gain medium, to shape the ultrashort pulses by inducing polarization-dependent loss, to manipulate the nonlinear frequency conversion by encoding the refractive indices via the frequent components of the pumping pulses in a birefringent crystal and so on.
Boian Andonov Hristov
Bulgarian Academy of Sciences, Bulgaria
Title: Exact analytical aberration theory of centered optical systems containing conic surfaces
Time : 10:00-10:20
Biography:
Boian Andonov Hristov is a Senior Research Fellow (Prof.) in Optics. His PhD is from Saint Petersburg State University of Information Technology, Russia. He had been member of the Faculty of the Military Institute of Optics and Laser Technology in Sofia, Bulgaria and member at the Institute of Optical Materials and Technology at the Bulgarian Academy of Sciences. He has published more than 60 papers in professional journals and proceedings from international conferences in Bulgarian, Russian and English. He is member of SPIE and has H-index 5.
Abstract:
The paper presents the development of exact analytical aberration theory (EAAT) of centered optical systems for conic surfaces such as oblate spheroid, sphere, ellipsoid, paraboloid, and hyperboloid. Provided are theorems of conjugate points and surfaces. We mean paraxial achromatic points, anastigmatic, plan sagittal, plan tangential, flat-field, orthoscopic, and surfaces with corrected tangential or sagittal coma which exist in the object and image space of every centered optical system, containing conical surfaces. To calculate the coordinates of the above mentioned points and surfaces in the object and image spaces of the optical systems we present accurate formulae. EAAT is able to correct one or several aberrations by calculating the constructive parameters such as radii and axial thicknesses. Furthermore, it is also possible for optical components or systems to be synthesized with precise corrected image aberrations and with given in advance object aberrations (to compensate the aberrations of preceding systems). Both the accuracy of the aberration correction and the calculation of the parameters (excluding tangential and sagittal coma) is about 10-10 mm. We present a variety of examples to illustrate the applied strength of EAAT. EAAT may be successfully used in all spheres of photonics and may accelerate drastically the research cycle in photonics technology.
Xinhua Peng
University of Science and Technology of China, China
Title: Quantum algorithms for factorization problem
Time : 10:20-10:40
Biography:
Xinhua Peng received her PhD degree in Atomic and Molecular Physics from Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, in July 2003. After that, she arrived at the University of Dortmund, Germany, as an Alexander von Humboldt Fellow. Since 2008, she is Professor at University of Science and Technology of China. She was awarded National Science Fund for Distinguished Young Scholars. She has published more than 50 papers in reputed journals.
Abstract:
Factorization of large numbers is a computationally hard problem on a classical computer: the computational resources required to accomplish this task increase exponentially with the size of the problem. Quantum computer could be much faster than classical ones in solving the factoring problem. Shor's algorithm is the most famous one. There are other methods for this problem, for example, adiabatic quantum algorithm and the Gauss-sum algorithm using properties of Gauss sums. Based on the idea of adiabatic quantum computation, we implemented the factorization of 143 by adiabatic quantum computation using nuclear magnetic resonance techniques, which is, we believe, the largest number factored in quantum-computation realization. On the other hand, relied on the properties of Gauss sums, we propose an efficient and exact quantum algorithm for finding the square-free part of a large integer - a problem for which no efficient classical algorithm exists. This algorithm overcomes the challenge that how to reduce the computational complexity by combining quantum entanglement with Gauss sums, and the introduced new concepts and methods may be applicable to a wider class of problems.
DO Tan Si
HoChiMinh-city Physical Association, Vietnam
Title: Fourier transforms of geometric forms and interference patterns, deflection of light by the sun
Time : 10:40-11:00
Biography:
DO Tan Si has completed his PhD in 1971 and is a Researcher at the Université Libre de Bruxelles and the Universíté de l’Etat à Mons (Belgium); Lecturer at the HoChiMinh-city Natural Sciences University (Vietnam) and is now retired. He researches on mathematics and concentrates on the differential transforms including almost the Fourier transform; on differential calculus for resolving differential equations, linking special functions with monomials, modernizing the Laplace transform and, in physics, is author of the paper “On amplitude of Fraunhofer diffraction of waves by 3D objects”.
Abstract:
Consider an object defined by a function equal to unity for a point inside a domain D and to zero for a point outside. Consider the diffraction of a plane wave by this object. The diffracted wave may be described by the function . The probability for finding a plane wave in the diffracted wave is proportional to the square of the integral over the whole space of , i.e., the Fourier transform of calculated for . The problem of calculating the amplitude of diffraction and interference patterns is thus reduced to that of calculating the Fourier transforms of geometric forms. The aim of this work is to popularize the method for performing these calculations which is based on the properties of the Dirac delta and the Heaviside functions, the reciprocal vectors as explained in the previous work “On amplitude of Fraunhofer diffraction of waves by 3D objects”. Results of calculations for the cases of a point, an array of points, an array of stripes, discs, array of spheres and ellipsoids, cones, cylinders, intersections of them are given, completing the results obtained in the previous work. An attempt to calculate the angles of deflection of light by the form of the sun is also done and perhaps shows that the deflection given by General relativity is the sum of those by the form and the mass of the sun?
Giuseppe Antonacci
Centre for Life Nano Science, Italy
Title: Brillouin microscopy for sub-cellular 3D mechanical imaging
Time : 11:15-11:35
Biography:
Giuseppe Antonacci has completed his PhD from Imperial College London. He is a Research Associate at the Italian Institute of Technology and is an Editor for the De Gruyter Physics.
Abstract:
Brillouin spectroscopy has shown great potential to become a reliable diagnostic tool due to its capability of measuring viscoelastic properties of materials in a non-contact manner. The recent development of high-sensitivity CCD cameras and Virtually Imaged Phase Array (VIPA) etalons has dramatically reduced data acquisition time to ~0.1 sec per spectrum. This has brought Brillouin spectroscopy from a point sampling technique to a new imaging modality. We describe the characterization of a confocal Brillouin microscope designed to measure mechanical properties of biological tissues. The frequency broadening of the Brillouin spectrum due to high illumination and collection apertures has been investigated in order to determine the optimal geometry that maximizes both the spectral and the optical resolution. A high extinction ratio was achieved in a Michelson interferometer to suppress strong specular reflections. Sub-micron resolution Brillouin images of single cells and arterial wall tissues have been acquired, in particular when atherosclerotic plaques were formed. These results might encourage the application of Brillouin microscopy as a tool of choice in clinical practice.
Weigang Hou
Northeastern University, China
Title: Router and routing designs for 3D torus optical network on chip
Time : 11:35-11:55
Biography:
Weigang Hou has completed his PhD from Northeastern University (China) School of Computer Science and Engineering. He was the Research Associate from City University of Hong Kong Department of Computer Science. He is currently the Associate Professor of Northeastern University (China). His research topics including elastic optical network, optical data center network, optical network on chip, space information network and software-defined optical network. He has published more than 50 papers in conferences and journals including IEEE/OSA JLT, IEEE/OSA JOCN, IEEE Network, IEEE Globecom, IEEE ICC, etc.
Abstract:
With the rapid development of electronic products, the high-speed computing applications pose greater demands of the on-chip performance, which cannot be coped with the Network on Chip (NoC) because of its inherent limited bandwidth and low communication efficiency. Recently, the Optical NoC (ONoC) has emerged as a promising solution. Furthermore, 3-Dimensional (3D) ONoC was proposed to reduce the communication conflict among the significantly increasing number of Intellectual Property (IP) cores on the ONoC. However, current optical routers with 3D ONoC topology have redundant crossbars, and the routing algorithm lacks agility and relies on the deterministic strategies without the awareness of the network status. More importantly, the previous routing algorithms were designed with the objective to either minimize the power consumption or transmission delay. Different from large-scale optical networks, the OnoC pays more attention to its transmission reliability, since the wavelength drift will occur if the heat dispersion varies, which deteriorates Signal-to-Noise Ratio (SNR). In this paper, we propose new bidirectional and vertical optical routers for 3D Torus topology, in order to save chip resources. Then, we model the structure of these routers and propose corresponding routing algorithms. The microcosmic packet forwarding algorithm is utilized for each kind of router, meanwhile, the power loss and crosstalk on the optical signal along the light path are analyzed in our adaptive macroscopic routing, with the consideration of thermal-sensitive wavelength drift. Our mathematical analysis and simulation results demonstrate the effectiveness of our methods. Especially, the effectiveness of our routing algorithm is demonstrated via bound analysis.
E U Rafailov
Aston University, UK
Title: New generation of a single-chip LEDs with superior colour rendering emission
Time : 11:55-12:15
Biography:
E U Rafailov received the PhD degree from the Ioffe Institute. In 2005, he established new group and in 2014, he and his Optoelectronics and Biomedical Photonics Group moved to Aston University. He has authored and co-authored over 400 articles in refereed journals and conference proceedings. He has coordinated a €14.7M FP7 FAST-DOT project – development of new ultrafast lasers for Biophotonics applications. Currently, he coordinated the €11.8M NEWLED project which aims to develop a new generation of white LEDs. He also leads a few others projects funded by FP7 EU and EPSRC (UK). His current research interests include high-power CW, ultrashort-pulse lasers; generation of UV/visible/IR/MIR and THz radiation, nano-structures; nonlinear and integrated optics; Biophotonics.
Abstract:
Development of LED-based solid state lighting has led to understanding that various lighting applications provide very different requirements to the quality and characteristics of white light. The mainstream applications, like outdoor (street) and indoor lightings are primarily aimed at saving electricity consumption and, therefore, need maximum efficacy and minimum cost of white-light source. Warm-white emission with superior CRI is demonstrated using a di-chromatic monolithic InGaN multiple quantum well LED and two phosphors. The LED emitting simultaneously blue (440 nm) and cyan (480 nm) photons pumps the vertically stacked red (~ 620 nm) and green (~540 nm) phosphor. An excellent average colour rendering index, CRI (Ra) of 98.4 with CCT of 3400 K is achieved. With appropriate heat sink assembly and industry standard packaging to improve extraction efficiency we estimate these devices can achieve Luminous Efficacy and Wall-plug Efficiency (WPE) of more than 160 lm/W and 55% respectively.
Sanjeev Kumar Raghuvanshi
Indian School of Mines, India
Title: Photonic microwave arbitrary waveform generation with adjustable chirp parameter based on remote sensing applications
Time : 12:15-12:35
Biography:
Sanjeev Kumar Raghuwanshi is working as an Assistant Professor in the Department of Electronics Engineering at Indian School of Mines, Dhanbad since March 2010. He has completed Post-doctorate at Instrumentation and Sensor Division, School of Engineering and Mathematical Sciences, Northampton Square, City University, London. He obtained PhD degree in the field of Optics from the Department of Electrical Communication Engineering of Indian Institute of Science, Bangalore, India. He has published more than 200 papers in reputed journals and conferences and serving as an Editorial Board Member of repute.
Abstract:
The objective of this paper deals with various methodologies for generation of photonics microwave waveform using adjustable chirp parameter. In this paper, the research efforts have been focused on the investigation of innovative optical techniques to generating and processing high frequency and large bandwidth (extended from E band to K band with adjustable chirp factor) microwave arbitrary waveforms using advanced Fibre Bragg Grating (FBGs) with single and cascaded Mach Zehnder Modulators (MZM). Photonic generation of microwave arbitrary waveforms based on coherent optical pulse shaping using advanced FBGs is proposed to be studied experimentally and theoretically. Two different methods for photonic microwave arbitrary waveform generation (with single and cascaded MZM configuration) are proposed to be investigated. Advanced FBGs have been employed in the systems as an optical spectral filters and dispersive elements. Different types of FBGs are proposed to be investigated, which have a very important role in the proposed microwave arbitrary waveform generation and processing systems, with the advantages of small size, low loss, low cost, good stability, and high compatibility with other well developed fiber optic devices. Besides it dispersion is one of the major limiting factors for the microwave signal generation in microwave photonics. Theoretically, influence of higher order dispersion parameters on microwave signal generation has been investigated under this talk for the case of single and cascaded MZM configuration. The FBGs have to be incorporated into the proposed systems to achieve microwave arbitrary waveform generation and processing.
- Optical Sensor Technologies and Types | Medical Laser Technology | Optometry Practice
Location: July 29, 2016- Embassy I+II
Chair
German F de la Fuente
ICMA CSIC-University of Zaragoza, Spain
Co-Chair
Daniel Valverde
University of Guayaquil, Ecuador
Session Introduction
Daniel Valverde
University of Guayaquil, Ecuador
Title: Importance of early diagnosis Retina
Time : 12:35-12:55
Biography:
Daniel Valverde is presently working as a Faculty of Medical Sciences at University of Guayaquil. He is a specialist in retina medicinal, ocular nutrition, low vision, pediatric vision, public health and many community development projects in public health. He is a fellow member in Public Health of Inter-American University of Puerto Rico. He has completed his Continuing Education from The New England College of Optometry, Boston, USA. He is a member of the AOA American Optometric Association, International Council of Ophthalmology, Ophthalmology Education Committee, Ocular Nutrition Society USA and OSH President. He is a Lecturer in North America, Central America, South America, Europe and Asia.
Abstract:
One area that has been somewhat neglected in clinical practice of optometry is undoubtedly the retina. This being the main axis where vision develops, certainly you have to consider this fact. In our offices, there is no need of any sophisticated equipments, we can have a direct ophthalmoscopy to determine what we see and how we see. This provides early diagnosis for allowing us to provide our patients the opportunity to prevent permanent blindness. Management of preventive actions with antioxidants and ocular nutrition certainly gives us another stage start in the fight against prevention of blindness. Recall that in the levels of patient care, designed by the World Council of Optometry, approved in Dallas Texas in 2006, is set to the third level of care the patient's ocular diagnosis as a tool of action in clinical practice. We know that today Europe has experienced great development in the training of optometry, but we also know that not all countries of the continent are experiencing this academic development, which drives us to achieve standardization in clinical practice, and the early diagnosis of problems in retina makes a big difference in what we see? How we see? What we are shown? Because the retina is the key to success, finding a healthy retina and differentiating it from some problems for referral to retinologist gives the patient a great alternative.
German F de la Fuente
ICMA CSIC-University of Zaragoza, Spain
Title: The laser furnace: Enabling continuous processing of ceramics and glass under extreme conditions
Time : 12:55-13:15
Biography:
Germán F de la Fuente is a Research Professor at the Spanish National Research Council (CSIC) working at the Aragón Institute for Materials Science (ICMA). He started the Laser Applications Laboratory at ICMA about 25 years ago, a reference in Laser Ablation and Melting and has developed large area laser surface coating and modification methods for ceramics, glasses and metals. He is co-inventor of 10 patents, coauthor of 140+ scientific papers and has coordinated a large number of projects based on the use of laser technology developed in his research group.
Abstract:
Laser processing of ceramics and glass has been proposedas a method to enable a multitude of surface functionalities and unforeseen relevant applications, although laser-induced thermal shock has hindered full use of lasers within these industrial sectors. Most of the former materials suffer cracking and eventually, catastrophic failure as a consequence of accumulated thermo-mechanical stress. In order to avoid this problem, a patented device has been developed which combines continuous laser scanning with uniform movement of the samples across a roller kiln kept under a convenient temperature profile. This unprecedented methodology enables treatment of any surface at extreme temperatures, while the sample’s volume is kept at reasonably low temperatures. For example, BaZrO3 coatings melting near 3000ºC have been processed over Al2O3 substrates at temperatures around 2100ºC or over porcelain tiles at 1140ºC, insuring very robust coatings integrated at the atomic scale into the substrate. This talk will present the Laser Furnace models developed so far and will review the most relevant results obtained to date in glass and ceramics.
Nezar R Damati
Eyezone Institute of Opticianry and Private Training, Kuwait
Title: Scleral contact lens for KC management
Time : 13:55-14:15
Biography:
Nezar Damati completed MBA degree. He is a Doctor of Optometry, Professional Academic Educator, highly motivated Optometrist, CL Practitioner and Consultant in fitting for the most prestigious clinics and optical chains. He has extensive experience in ECP, an exposure in CL education, and training programs on leadership in CL fitting. He is a Certified International Professional Trainer and Executive Director at Eyezone Institute of Opticianry and Private Training, Kuwait.
Abstract:
Learning Objectives: Upon completion of this program, the participant should be able to understand the new generation of large RGP design lenses; learn more about fitting techniques for scleral lenses and understand the indication and patient candidate of scleral lenses. Course Description: Keratoconus, often referred to as “KC,” is a slowly progressive, non-inflammatory eye disease that causes the cornea to thin and assumes an irregular conical shape appearance. The cornea refracts the majority of light that enters the eye so abnormalities or injuries to the cornea can significantly affect patient vision and impair the ability to perform simple tasks and duties like driving (especially night driving), daily activities, watching TV, or reading a book. This course describes keratoconus and treatment with RGP scleral contact lenses. Conclusion: Fitting the keratoconus patient is challenging. Scleral lenses represent one of the most important tools available to fitters today. Their use should continue to increase because they offer excellent vision, good initial comfort, and they eliminate concentration related problems that can occur with smaller diameter lenses.
Nianwen Cao
Nanjing University of Information Science and Technology, China
Title: Aerosol profiling by Raman Lidar in Nanjing, China
Time : 14:15-14:35
Biography:
Nianwen Cao has completed his PhD from Anhui Institute of Optic & Fine Mechanics, Academic of Science of China. He is a Professor, engaged in Atmospheric Remote Sensing by Lidar, at Nanjing University of Information Science & Technology. He has published more than 40 papers in reputed journals.
Abstract:
The aerosol measurements by using Raman-Mie-Rayleigh Lidar in Nanjing, China, were presented in this paper. The Lidar system consisted of transmission at 532 nm and receiver with 3 different channels. The aerosol Lidar signals generated from backscatter lights were obtained simultaneously from Raman (607 nm)-Mie (532 nm)-Rayleigh (532 nm) Channels. Aerosols at low/high altitude were measured by Mie/Rayleigh Channel at daytime, and measured by Raman Channel at night time. The start of data collection of Rayleigh & Raman Channel was controlled by the gate by setting different time delay. New aerosol extinction coefficient calculation methods by using Mie/Rayleigh Channel data were reported. According to the structure of Range corrected signal from Mie/Rayleigh Channel, the accurate extinction coefficient at the range of homogeneous aerosol layer was obtained, then, to be used as reference value to calculate the aerosol extinction coefficient profiles at whole range. The accurate aerosol extinction coefficient profile was obtained by comparison of different aerosol extinction coefficient profiles by slightly changing the boundary values. The aerosol optic properties were also calculated from the signals from Raman Channel by using Raman theory after Lidar data treatment by using multi-average calculation or small wave analysis. The aerosol extinction coefficient profiles obtained from Mie/Rayleigh Scatter were compared with from Raman Scatter. The aerosol extinction coefficients about 10-4 ~ 10-5 were calculated from Mie/Rayleigh Channels coincided with Raman Channel. The boundary aerosol optic properties were obtained by Mie/Raman channels, and aerosol optic properties at higher altitude were measured by Rayleigh/Raman channels. Aerosol parameters at different altitudes were measured simultaneously from one measurement by Raman-Mie-Rayleigh Lidar/Multi-function Lidar system.
Victor V Apollonov
Prokhorov General Physics Institute, Russia
Title: New applications for high repetition rate high energy P-P lasers
Time : 14:35-14:55
Biography:
Victor V Apollonov is the leading specialist in the area of basic principles of creation and development of high energy laser systems and high energy laser radiation interaction with matter. He has made an outstanding input into creation and development of new branches of science - physical and technical fundamentals of high average power laser optics and adaptive optics, investigation of physical processes in a high volume self-controlled volume discharges, creation of high power continuous wave, pulsed and high repetition rate pulse-periodic laser systems, high energy laser radiation interaction with matter, and high energy laser application. He is the author of more than 1300 publications: 16 books, 368 presentations and 147 patents, 750 articles, (Research Gate). He is a full member of Russian Academy of Natural Science and Academy of Engineering Sciences, member of the Presidium RANS. He is the laureate of State Prize of USSR (1982) and of Russia (2002).
Abstract:
At present, we consider as most energetic and promising for high repetition rate pulse – periodic (P-P) laser applications carbon dioxide laser, chemical laser and solid-state laser. In the future, high-power high-frequency P-P lasers will find applications in the field of ecology of space. Besides, they will be used to transmit power over long distances, to obtain high-power plasma radiation in the range of ten to hundreds of Angstroms, to realize arbitrary geometry of the breakdown in a three-dimensional space, to produce ultrasound, electromagnetic fields etc. A new class of rocket engines – a laser jet engine (LJE) – objectively belongs to the most promising rocket engines of the foreseeable future. The LJE is substantially more cost-effective than conventional chemical fuel engines. At the initial stage of the flight, the LJE employs atmospheric air as a working medium and in outer space use is made of a small space-borne gas supply or an easily sublimated substance. In this case, the specific costs of the cargo launching to outer space may be reduced down to 150–300 USD/kg. The LJE-based solution of a series of very interesting and important problems is predicted, in particular designing of a space interceptor that would destroy debris and other dangerous space objects, such as asteroids, meteors, etc.; launching of macro-objects with a very high acceleration that is orders of magnitude greater than it can be done by existing technology; realization of super-long orbital-scale conducting channels for addressing the global challenges of ecology and energy transfer; laser-plasma generator of multiply charged ions produces a large number of heavy ions in the regime of short P-P pulses, which is of interest for ion accelerators operating in the P-P regime and many other applications of high energy P-P lasers.
Hee Kyung Ahn
Korea Research Institute of Standard and Science, South Korea
Title: Cascaded multi-dithering technique for high power beam combination setup
Time : 14:55-15:15
Biography:
Hee Kyung Ahn has completed his PhD from Korea Advanced Institute of Science and Technology (KAIST) and Post-doctoral studies from Korea Research Institute of Standard and Science (KRISS).
Abstract:
Coherent beam combination is a way to obtain high power by coherently adding lower power beam elements and has been highlighted as an alternative to scale up the power of high power and high beam quality lasers which has faced several problems such as thermal effect and nonlinear effects. For combining a large number of beam elements, It is inevitable to use active phase control, which is to lock phases of beam elements and obtain maximum output power. There are several methods in active phase control such as heterodyne detection, stochastic parallel gradient descent (SPGD) algorithm, multi-dithering technique, and single-dithering technique. Among those methods, locking of optical coherence by single detector electronic-frequency tagging (LOCSET) technique, as known as multi-dithering technique, locks the phases of beam elements by modulating the phases with different frequencies and demodulating the signal of the combined beam with those frequencies. It has showed excellent performance in terms of phase stability and the number of beam elements to be combined. However, the maximum number of beam elements to be combined is limited up to 100 to 200 when combining high-power amplified beam elements using LOCSET, since the number of modulating frequencies is limited 100 to 200 because of the constraint of the control bandwidth of phase locking system. Cascaded Multi-Dithering (CMD) technique has been proposed to solve this limitation, by modulating beam elements in series and combining them as a form of array. It was successfully demonstrated by combining sixteen beam elements in 2015. Nevertheless, CMD technique also has a limit to combine high-power amplified beam elements because of low damage threshold of phase modulators which dither high power beam elements after amplification. In this paper, a new setup of CMD technique for high power beam combination is presented. By simply changing the configuration of CMD technique, the problem of low damage threshold of phase modulators is easily solved, which enhances the capability of CMD technique as a powerful tool for combining a substantial number of high power beam elements.
Jafar Jahanpanah
Kharazmi University, Iran
Title: Investigation of distribution mechanism of noise fluxes between three oscillating modes of a free-running class –A laser
Time : 15:15-15:35
Biography:
Jafar Jahanpanah received the BSc degree in Applied Physics from Amir Kabir University, Tehran, Iran, in 1989, and the MSc degree in Optics Communication and the PhD degree in Laser Theory from Essex University, UK, in 1992 and 1995, respectively. He began his PhD research with Prof. R. Loudon with a focus on the gain, stability, and injection-locking topics in a single-mode laser amplifier. His current research interests include laser noise and also the gain, stability, and mode-locking phenomena in the multi-mode lasers. He has published many articles in journals of PRA, OSA, applied physics, optics communications, and IOP.
Abstract:
In this paper, the noise aspects of a class-A laser from the single mode state with one cavity damping rate are extended to the more general case of three-mode state with the three equal cavity damping rates.The cavity Langevin force is thus divided into three parts , , and associated with the simultaneous oscillations of cavity left, central, and right modes, respectively. In this way, the phase and amplitude fluctuations of cavity electric field components are analytically calculated by solving the three-mode Maxwell-Bloch equations of motion in the presence of three fluctuating cavity Langevin forces.The correlation functions of three latter cavity Langevin forces are then used to calculate the noise fluxes that are simultaneously superimposed on the mean energy fluxes of oscillating modes in the form of stimulated emission radiation. The most advantage of our calculations is to determine the exact share of each oscillating mode in the total noise flux spectra of laser, spontaneous emission, and pumping of a three-mode class-A laser. The results indicate that the cavity Langevin force of each of three oscillating modes makes a direct contribution in producing the noise fluxes of other two oscillating modes. Our model is finally confirmed by demonstrating a balance relation between the input pumping noise flux and the output noise fluxes of laser and spontaneous emission of three oscillating modes.
Kang Xueliang
Shandong University, China
Title: Research progress on metal ions doped lithium tantalate crystals and their applications in green laser
Time : 15:50-16:00
Biography:
Kang Xueliang received his Bachelor's degree at Shandong University in China in 2012 and has been studied in Institute of Crystal Materials of Shandong University as a Post-graduate student since then. His research focused on the growth, structure and physical properties of lithium niobate crystal and lithium tantalate crystal. He has published several literatures in some important journals.
Abstract:
Lithium tantalate (LT) is one of the most promising nonlinear optical materials. However, the low optical quality and damage threshold limits its application in photics. Therefore, growth of MgO doped LT and stoichiometric LT has become a hot research topic. Nd, Mg co-doped LT possess improved laser properties and these metal ions would help eliminate anti-site defect in crystals which affect the physical properties largely. However, the doping homogeneity is still a key factor which determines the quality of the crystals. Therefore, we focused on the research of crystal growth, ions doping and physical properties of lithium tantalate for years. We obtained MgO doped SLT and Nd, Mg co-doped CLT crystals with high homogeneity and great optical properties. We studied the anti-site defects in crystal lattice and elimination method. With the Nd, Mg co-doped CLT crystal, a CW laser output power of 3.58 W was achieved. A green laser with multi-wavelength emission was demonstrated using intracavity frequency conversion (frequency doubling and frequency summing) in a Nd:Mg:LiTaO3 laser. MgO-doped periodically poled lithium niobate (MgO:PPLN) was used as a nonlinear crystal in this work. Moreover, a 62mW that could emit light at 546, 542 and 538 nm was obtained by end pumping with a 808-nm laser diode. The speckle contrast ratio for the three-wavelength laser was only 3.36%, a quarter of the value of the conventional 532-nm laser, which showed that a multiwavelength broadband laser is an effective way to reduce the speckle noise in a laser projection display.
Tim Frijnts
Helmholtz Zentrum für Materialien und Energie Berlin, Germany
Title: Laser processing of solar cells on laser crystalized silicon
Time : 16:00-16:10
Biography:
Tim Frijnts has finished his MSc in Applied Physics at Delft University of Technology in 2010, after which he went to work as Device Expert at the thin film silicon solar cell company Masdar PV GmbH in Germany. At the end of 2013, he started his PhD at HZB/PVcmB (part-time), as part of an ambitious plan of Masdar PV and HZB to commercialize liquid phase crystallized silicon. When one year later Masdar PV decided to shut down, he had the opportunity to continue at HZB to finish his PhD.
Abstract:
Low quality silicon was deposited on silicon oxynitride layers on glass. This was then crystallized over a liquid phase using a line-shaped, 808 nm, continuous wave, diode laser, in order to obtain crystalline silicon with grain size comparable to multicrystalline silicon wafers. A 1064 nm picosecond laser, applied through the glass, was used to make isolation scribes which define the cell area and also allow for the fabrication of a mini-module consisting of series connected cells. A 355 nm picosecond laser, in combination with a white resin layer, was used to structure the contacting layers of the backside contacted solar cell, thereby avoiding the use of expensive and cumbersome lithography processes. Finally, a 532 nm nanosecond laser was used to modify the metal-silicon contact in order to reduce the contact resistance, resulting in a new highest efficiency for this cell type of 12%.
Héctor Santos Barahona
Complutense University of Madrid, Spain
Title: Surface alloying of Al coatings on P92 steels by laser line scanning
Time : 16:10-16:20
Biography:
Hector Santos finished his Master’s in Chemical Engineering in 2007 and has since been working at the Surface Engineering and Nano-structured Materials Research Group of the Complutense University of Madrid. He is currently starting 4th year of his PhD studies.
Abstract:
Conventional protective coatings for energetic applications (e.g. heat exchangers, certain turbine components) are highly exposed to severe degradation conditions. High steam pressure and temperature, typical of high performance operating regimes have a dramatic effect over the materials’ long-term lifespan. Within this context, further expansion of conventional materials performance is of utmost importance, especially when revamping of existing facilities is in sight. Herein, we present a recently developed laser line scanning method for surface alloying treatments, based on directional solidification of an intermetallic coating, particularly adapted for the Al/P92 steel system studied. Such conventional material system has been widely reported in the literature using different preparative approaches. Much less common has been the work on laser treatments, particularly on directional solidification. Such directionality is partially achieved by processing samples at traverse rates with values ranging between 30 and 300 mm/h. Undesirable effects associated to aluminium oxide formation are reduced by using a controlled atmosphere chamber during laser surface alloying. This advanced laser line scanning method offers the means to effectively control the microstructure, surface and adherence properties of Al/P92 protective coatings.
Khaled M Saoud
Virginia Commonwealth University in Qatar, Qatar
Title: Utilization of continuous low power visible laser in the 3D printing of strong and ultra- light weight cross-linked silica aerogel
Time : 16:10-16:20
Biography:
Khaled M Saoud is Associate Professor of Physics at Virginia Commonwealth University in Qatar. He has completed his PhD in 2005 in Chemical Physics at the Chemistry and Physics departments, Virginia Commonwealth University. He held many industrial positions at major American companies such as Philip Morris USA, Intel Corporation, and Nova Measuring Instruments Inc. He has been working in the field of Nanotechnology since 1998. He published over 40 research papers in the field of Nanotechnology and holds two US patents.
Abstract:
3D printing of strong and lightweight materials is playing an increasingly significant role in many applications such as the 3D printing of designs and prototypes, architectural models, consumer products, electronics, and printing technologies. Various materials and methods have been explored for 3D printing such as laser sintered metals, photo-cross-linked polymers and extruded molten polymers. Recently, lasers, laser-assisted 3D printings are getting much attention over traditional methods of 3D printing due to their flexibility and efficiency. Current 3D involve the use of a high power and pulse lasers such as carbon dioxide laser or ultraviolet lasers (UV). In this paper, we present the synthesis of polymer cross-linked silica alcogels in a matter of seconds by illuminating a precursor solution of an alkoxide, a monomer and a visible-light photo-initiator using a 2 Watt laser beam (532 nm). The illumination initiates free-radical polymerization then the heat of polymerization triggers gelation instantly. We have successfully demonstrated a manual printing of 3D letters on different substrates like laminated paper, a glass slide and a silicon wafer using masking techniques, and also the printing of a 50 mm thick line on a glass substrate through direct shining of a laser on the liquid mixture without any mask. Our results indicate that the instantaneous and simultaneous polymerization and gelation of silicon alkoxide precursor and polymer can lead to the fabrication of mechanically strong and ultra-lightweight silica aerogels which offers a new direction for the 3D industry.
Naimi E K
National University of Science and Technology “MISISâ€, Russia
Title: 4D-Photonic crystals
Time : 17:35-17:55
Biography:
Naimi Е K received PhD from Moscow State University and Dc. Sc. thesis from Moscow Institute of Steel and Alloys in 1993. In 1994, she worked as a Professor in Department of Physics. Her fields of research interests are solid state ultra-acoustics. She has published more than 50 papers in reputed journals.
Abstract:
One of the modern optics directions is the investigation of the so-called photonic crystals (PCs), a new class of ordered optical materials characterized by two main features: the periodic spatial modulation of the refractive index with a period allowing light Bragg diffraction and the existence of band gaps associated with translational symmetry of the refractive index in the spectrum of intrinsic electromagnetic states. The idea of the PC development belongs to E. Yablonovich and S. John (1987). It consists in designing new artificial media whose properties would make it possible to affect photons similarly to the effect of the ordinary lattice on electrons. Similarly to Bloch waves of electrons in ordinary crystals, optical waves in the PC lattice can have states in which the wave vector k (phase velocity) direction and the Poynting vector (group velocity) direction are anti-parallel. In other words, PCs can have a negative refractive index. The phenomenon of negative light refraction was most thoroughly considered by V.G. Veselago (1967). From the general point of view, the PC is a super lattice, i.e., a structure in which an additional field with a period exceeding the period of the basic lattice by several orders of magnitude is artificially induced. For photons, such a field is induced by periodic changes in the refractive index of the medium in one, two, or three dimensions (1D-, 2D-, and 3D-photon structures). The formation of dynamic periodic changes in the PC structure makes it possible to one more dimension, i.e., the time. A crystal obtained in such a way can be considered as a four dimensional (4D) photonic structure where the time is the fourth dimension. Due to the mutual influence of spatial and temporal processes, optical properties of such structures are potentially more diverse than properties of three dimensional crystals. In the present work we consider the conditions of the formation of the dynamic PC based on an optically homogeneous and isotropic medium with space–time modulation of the refractive index, implemented by an ultrasonic wave whose length exceeds the light wavelength by many orders of magnitude. To solve the posed problem in general form, we use Fermat’s principle. It has been shown that the excitation of a standing ultrasonic wave in the medium creates a structure consisting of trajectories of separate light beams, which is a super lattice of the dynamic 4D-photonic crystal. The band gaps corresponding to negative light refraction have been revealed in beam trajectories. Possible fields of application of such structures have been discussed.
Mikhail A Bisyarin
St.Petersburg State University, Russia
Title: Analytical approaches to description of nonlinear processes in inhomogeneous optical waveguides
Time : 17:55-18:15
Biography:
Mikhail A Bisyarin has received his Doctor of Science (Phys. & Math.) degree in 2010 and continues his studies at St. Petersburg State University. He is a Head Researcher at the Department of Radiophysics and carries out research on analytical methods in the theory of non-linear oscillations and waves. He has published about 50 papers in reputed journals and has co-authored (with I. A. Molotkov and S. A. Vakulenko) the monograph entitled “Nonlinear Localized Wave Processes” (in Russian).
Abstract:
Despite a wide outspread of applied programming packages, the development of analytical methods for description of the nonlinear regime of the short modulated pulse propagation in a graded-index dielectric waveguide with longitudinal inhomogeneity remains an urgent problem. These are the analytical approaches that enable to study the very structure of the propagation process, each its component separately and their interaction, as well as to clarify the effects of various physical factors into the travelling pulse parameters. The pulse under scrutiny appears to be a sinusoid of an optical frequency with an envelope covering from several units through several tens of oscillations (sub-picosecond pulses), with the phase modulation, e.g. chirp, being also allowed. Considered as a propagation medium, is a graded-index waveguide - a planar or cylindrical dielectric with the refractive-index profile providing the wave field localization within the waveguide cross-section. The refractive index is supposed to depend on the longitudinal coordinate, and a slight bending of the waveguide axis is also allowed. The asymptotic technique proceeds from the generalized nonlinear wave equation, uses a unique small parameter, and allows in a natural way to extract a linear component of the process. This linear task defines the mode structure of the pulse, i.e. the propagation constant and the field distribution within the graded-index waveguide cross-section. A more realistic sech-refractive-index profile (instead of quadratic) is involved into analysis, nevertheless explicit formulae are derived in this case. The nonlinear pulse dynamics is characterized by a generalized nonlinear Schroedinger equation, its coefficients depend on material and waveguide dispersion and are functions on the longitudinal coordinate. This is substantial in taking into account the longitudinal inhomogeneity in describing the nonlinear pulse dynamics.