Day 1 :
Director of School of Photonics ITMO University Russia
Keynote: Wide band-gap semiconductor materials with low defect density for future high-power nanophotonics and electronics
Time : 08:55-09:20
Vladislav E Bougrov is the Director of School of Photonics and Head of Chair of Light Technologies and Optoelectronics at the ITMO University, St. Petersburg, Russia. He has obtained his Master’s degree in Optoelectronics from Department of Optoelectronics, PhD in 1999 and DSc in Physics in 2013 from Ioffe Institute, St. Petersburg, Russia. He is the author of more than 60 papers in reputed journals, inventor of more than 100 patent applications, including more than 30 granted patents and has extensive experience with dynamic management of growing international start-up companies. He is the founder of Optogan.
Wide band-gap (WBG) semiconductor material scientific and technological research has greatly intensified over the last decade due to their tremendous potential for electricity savings offered by WBG semiconductor materials and devices for solid state lighting (SSL) and power electronics (PE) for grid-scale applications. Replacement of today’s light sources with nitride-based SSL offers 10-15% electrical energy savings potential, however, requiring breakthroughs in materials, devices and lighting systems. Similarly, grid-scale implementation of WBG PE offers 10% electrical energy savings through the reduction in power conversion losses in the grid, requiring development of the science and technology of WBG PE devices. To address this opportunity, our group focused mainly on two WBG materials systems: III-nitrides and β-Ga2O3. One of the major problems during WBG material and device development is high defect density typically observed in WBG materials. Nano-photonic and electronic devices fabricated from high dislocation density layers demonstrate poorer performance than those made from relatively defect-free layers. Light emitting diode (LED)-based SSL is usually realized by combining blue III-nitride LED light with yellow and red light from down-converting phosphors. The typical LED efficiency is on the order of 100–140 lm/W at low currents, and it falls with injected current density due to the droop phenomenon. To assess possible progress, it suffices to know that the efficiency limit for LED is about 300lm/W. One of the main reasons for efficiency droop is an extremely high density of threading dislocations (TDs). High density of TDs results from the initial inevitable step of epitaxial growth of GaN layer on foreign substrates possessing high lattice mismatch, e.g., sapphire or silicon carbide substrates. We develop a general methodology for the reduction of TD density in III-nitride layers fabricated in (0001) polar growth orientation. We present the results on theoretical and experimental studies of threading dislocations (TDs) behavior in III-nitride layers grown in polar orientation. TDs are defects formed during epitaxial growth of layered electronic and optoelectronic materials. In PE, the full potential of WBG materials can only be realized by using single crystal substrates. Although some commercial devices have been demonstrated, the optimum material/device structure for the MW power applications has not yet been defined. β-Ga2O3 due to its reasonable carrier mobility and extraordinary high dielectric breakdown strength, offers clear advantages compared both to Si-based devices and other WBG materials. β-Ga2O3 is the only stable polymorph of gallium oxide through the whole temperature range till the melting point. We report flat-surface β-Ga2O3 single crystals produced by free crystallization of Ga2O3 melt.
Leverhulme Chair, Imperial College London, UK
Keynote: Title: Dynamics of plasmonic nanolasing: From strong coupling to stopped-light lasing and surface-plasmon polariton condensation
Time : 09:20-09:45
Ortwin Hess is currently the Leverhulme Chair in the Blackett Laboratory (Department of Physics) at Imperial College London. He has obtained his PhD degree from the Technical University of Berlin (Germany) in 1993 and the Habilitation from the University of Stuttgart in 1997. From 2003 to 2010, he was a Professor at the University of Surrey (Guildford, UK) and a Visiting Professor at Stanford University (1997/98) and at the Ludwig-Maximilians University of Munich (1999/2000). He is the author of more than 170 journal papers, 3 books and 23 book chapters and has presented 15 plenary talks and over 90 invited talks at international conferences.
Recent progress in nanophotonics and metamaterials physics is now allowing us to ‘look inside the wavelength’ and exploit active nanoplasmonics and metamaterials as a new route to quantum many-body optics on the nanoscale. At the same time, lasers have become smaller and smaller, reaching with the demonstration of plasmonic nanolasing, scales much smaller than the wavelength of the light they emit. Here we discuss recent progress in the study of quantum emitters and quantum gain in nanoplasmonic systems and deliberate on approaches. We combine classical and quantum many-body theory and simulation to describe and model the spatio-temporal dynamics of the optical near field and plasmon polaritons coupled with quantum emitters in nano-plasmonic cavities. We reveal the mechanisms that recently have experimentally allow us to reach the strong coupling regime at room temperature and in ambient conditions. Moreover, it will be demonstrated that applying the nanoplasmonic stopped-light lasing principle to surface- plasmon polaritons (SPP) allows the realization of trapped/condensed non-equilibrium surface-plasmon polaritons at stopped-light singularities, providing an entry point to SPP-condensation.
Ioffe Institute, Russia
G S Sokolovskii is the Leading Research Fellow at Ioffe Institute (St.Petersburg, Russia). He has graduated from the St. Petersburg State Electrotechnical University ‘LETI’ (St. Petersburg, Russia) in 1994 (MSc) and has received his PhD and Doctor of Science (Habilitation) degrees from Ioffe Institute (1998 and 2010, respectively). His main research interests include Laser Physics, Nanophotonics and Physics of Semiconductors. He has authored and co-authored over 200 peer-reviewed publications and 10 patents on these topics. He is the Professor of the Russian Academy of Sciences and serves as the Vice-chair and Treasurer of the St. Petersburg Chapter of IEEE Photonics Society.
Frequency doubling of the infrared laser light based on the generation of new laser wavelengths via material’s nonlinearity is one of the most attractive ways for the realization of compact visible laser sources with a number of cutting-edge applications, which are supported both by the market and the technology via availability of compact and highly-efficient infrared laser diodes. However, for efficient conversion, or second harmonic generation, both photon and momentum conservation are to be achieved simultaneously. The last requirement (also called “phase-matching” constraint) is difficult to achieve due to dispersion of the refractive index in the nonlinear crystal. To date, by far the most commonly used approach for the phase-matching between interacting waves is the periodical poling (or “quasi-phase-matching”) of the ferroelectric nonlinear crystals by periodically reversing the crystals polarization under large electric field. In this talk, we provide a fundamental generalization of quasi-phase-matching based on the multi-mode matching and fractional-order poling techniques. With these techniques, an order-of-magnitude increase in the wavelength tunability range for frequency conversion from a single crystal is enabled, thus offering a preferred way for the realization of a compact and spectrally-flexible laser sources in the visible wavelength range.
Professor Institute of Electronic Materials Technology, Poland
Time : 10:10-10:35
Dorota A Pawlak is a Professor at the Institute of Electronic Materials Technology (ITME) of Warsaw, and at the Centre of New Technologies (CeNT), University of Warsaw in Poland. She is currently the Head of the Department of Functional Materials at ITME and Leader of the Laboratory of Materials Technology at CeNT. Her research is linked to technology development for the manufacturing of new functional materials, such as plasmonic materials, metamaterials, materials with special electromagnetic properties and materials for solar energy conversion. She currently focuses on bottom-up methods such as directional solidification and crystallization, nanoparticles direct doping method and associated research.
Professor Jan Czochralski investigated the crystallization velocity of metals from the melt, for this he developed a crystallization method in 1916, published in 1918, which later has been used by Teal and Little in Bell Laboratories to grow first germanium crystal. This good quality crystal enabled formation of first p-n junction and design of the first point-contact transistor. J Bardeed, W H Brattain and W B Shockley for the discovery got the Nobel Prize in physics in 1956. Currently, the Czochralski method is the most widely used crystal growth technique and Czochralski is often called the father of electronics. Recently it has been proposed to utilize crystal growth methods for manufacturing of novel photonic materials including plasmonic materials and metamaterials. Utilizing eutectic directional solidification such pivotal for metamaterials structures were demonstrated as split-ring resonators. Nanoplasmonic materials with tunable localized surface plasmon resonance and enhanced photoluminescence were demonstrated with an example of Bi2O3-Ag eutectic. Typical for eutectics geometry is lamellar or rod-like, and in this type of structures subwavelength transmission has been demonstrated, and hyperbolic dispersion predicted. Even growth of lamellar eutectics with a rounded structure has been demonstrated resembling the metamaterial hyperlens. Recently, a new approach demonstrated combining the eutectic crystallization with photonic crystal templates, thus enabling a two orders of-structuring of the material. Also, directional solidification has been applied for a novel method of manufacturing dielectric bulk materials doped with various nanoparticles called nanoparticle direct doping. With this method nanoparticles enter the dielectric matrix without a chemical reaction, thus the method enables doping the matrices with nanoparticles or various chemical composition, nanoparticles with specific shape, as well as co-doping with other chemical elements i.e. as rare earth ions. Utilizing crystal growth application for manufacturing of novel photonic composites may enable their easy application