Subwavelength grating metamaterial (SGM) is formed by interleaving two or more types of materials with a period far less than the operating wavelength. It offers an additional degree of freedom to customize the optical properties of naturally existing materials and develop integrated photonic components with unprecedented applications. In this paper, we introduce the design and implementation of SGM based silicon photonics devices. Silicon provides high index contrast and thus the footprints of silicon photonic devices can be made very small. However, high index contrast is a double-edged sword as it also leads to a few limitations such as limited photon-matter interaction and high dispersion. SGM waveguide can potentially resolve these issues. For instance, leveraging the enhanced photon-matter interaction within SGM, silicon-organic hybrid SGM modulator demonstrates > 44 GHz 6 dB bandwidth and estimated energy consumption of 2.55 fJ/bit. SGM waveguide based refractive index sensors exhibit eminent improvement on the sensitivity compared to conventional strip waveguide based sensors. In the meantime, unlike evanescent wave based sensors, the surface sensitivity of SGM sensors does not decrease as analytes accumulate on the waveguide surface. SGM waveguide based passive components show improved bandwidth due to the decrease of waveguide dispersion. Other potential applications of SGM will also be discussed.
Keywords: Subwavelength Grating Metamaterial, Silicon Photonics, Sensor, Silicon-Organic Hybrid Modulator, Ring Resonator

Ray Chen is the Keys and Joan Curry/Cullen Trust Endowed Chair at The University of Texas Austin.
Chen is the director of the Nanophotonics and Optical Interconnects Research Lab, at the Microelectronics Research Center. He is also the director of the AFOSR MURI-Center for Silicon Nanomembrane involving faculty from Stanford, UIUC, Rutgers, and UT Austin. He received his BS degree in Physics in 1980 from the National Tsing Hua University in Taiwan, his MS degree in physics in 1983, and his PhD degree in Electrical Engineering in 1988, both from the University of California. He joined UT Austin in 1992 to start the optical interconnect research program. From 1988 to 1992 Chen worked as a research scientist, manager, and director of the Department of Electro-Optic Engineering at the Physical Optics Corporation in Torrance, California.

Light-matter interactions are the fundamental basis for many phenomena and processes in optical devices. Ultra-high-quality Whispering-gallery-mode (WGM) optical micro-resonators provide unprecedented capability to trap light in a highly confined volume smaller than a strand of human hair; a light beam can travel around the boundary of a WGM resonator over 10^6 times, significantly enhancing light-matter interactions, creating the potential for a wealth of new scientific discoveries and technological breakthroughs for a variety of fields of science, spanning from communication to non-Hermitian physics, sensing and metrology. In this talk, I will present a few cases demonstrating the great potentials of high-Q WGM microresonators and microlasers for both fundamental science and engineering applications. I will start with the discussion of ultra-high-Q microresonators and microlasers for ultra-sensitive detection of nanoscale objects. Afterwards, I will discuss our recent exploration of fundamental physics, such as parity-time symmetry (PT-symmetry) and light-matter interactions around exceptional points (EPs) in high-quality WGM resonators, which can be used to achieve a new generation of optical system enabling unconventional control of light flow. Examples including nonreciprocal light transmission, loss engineering in a lasing system, directional lasing emission, and EPs enhanced sensing, will be introduced. A non-Hermtian phonon laser tuned in the vicinity of EPs will be discussed briefly. In the end I will present a new generic and hand-held microresonator platform transformed from a table-top setup, which will help release the power of high-Q WGM resonator technologies.

Professor Lan Yang is the Edwin H. and Florence G. Skinner professor in the Preston M. Green Department of Electrical and Systems Engineering at Washington University, St. Louis, MO, USA. She received B.S. from the University of Science and Technology of China and received her Ph.D. in applied physics from Caltech in 2005. Her research interests have been focusing on the fundamental understanding of high-quality photonic whispering-gallery-mode (WGM) resonators and their applications for sensing, lasing, light harvesting, and communications. Recently, her research interests expanded to parity-time-symmetry and non-Hermitian physics in high-quality WGM resonators, which have led to a series of new discoveries for unconventional control of light transport in photonic structures. She is the recipient of the 2010 Presidential Early Career Award for Scientists and Engineers (PECASE) for her work on chip-scale microlasers and her pioneering studies of nanoparticle detection using high-quality optical resonators. She has published ~100 papers in peer-reviewed journals, including Science, Nature, Nature Photonics, Nature Nanotechnology, Nature Physics, and PNAS, etc. She is a fellow of the Optical Society of America (OSA). Currently, she serves as the editor-in-chief of Photonics Research.

For a comprehensive understanding of complex semiconductor heterostructures and the physics of devices based on them, a systematic determination and correlation of the structural, chemical, electronic, and optical properties on a nanometer scale is essential. Luminescence techniques belong to the most sensitive, non-destructive methods of semiconductor research. The combination of luminescence spectroscopy – in particular at liquid He temperatures - with the high spatial resolution of a scanning transmission electron microscope (STEM) as realized by the technique of low temperature cathodoluminescence microscopy in a STEM (STEM-CL), provides a unique, extremely powerful tool for the optical nano-characterization of quantum structures.
Testing the spatial resolution limit in cathodoluminescence, we concentrate on highly spatially resolved luminescence characterization of a deep-UV emitting quantum well stack. 100 periods of GaN/AlN multiple quantum wells have been grown by MOCVD. The monolayer-thick GaN films are separated by 10 nm AlN barriers. STEM analysis evidences the high structural quality with abrupt interfaces and monolayer thickness of the GaN QWs. The thick QW stack shows intense emission at 228 nm at 17 K. In cross section, the CL intensity clearly correlates with the position of each individual QWs. The exceptionally small CL profile width of 2.8 nm indicates an efficient confinement of the wells. As a result, STEM as well as CL images clearly resolve the separation of QW with a distance of 10.8 nm.

TBA

The ability to arbitrarily shape femtosecond pulses with large bandwidth and high spectral resolution holds great potential for both studying fundamental light-matter interactions and developing real-world applications. A femtosecond pulse is defined by its phase, amplitude, and polarization. It has recently been demonstrated that dielectric metasurfaces can simultaneously and independently manipulate the phase and amplitude of a near-infrared femtosecond pulse having over 200 nm ultra-wide bandwidth while maintaining high spectral resolution of 0.3 nm [1]. Here, we further extend this work to offer the first experimental demonstration of femtosecond polarization pulse shaping using dielectric metasurfaces by controlling the temporal polarization state within a single pulse. The pulse shaper consists of a Fourier-transform setup with a dielectric metasurface positioned in the focal plane. The metasurface is formed of arrays of rectangular silicon nanopillars whose dimensions are carefully designed to deliver the targeted spectral phase for two orthogonal polarizations. A pulse of linearly polarized input light is orientated 45° with respect to the nanopillars, providing two equal polarization components. After passage through the metasurface, the shaped output pulse is characterized by direct electric-field reconstruction using spectral phase interferometry. The output pulse contains both polarization components. As a result, after the metasurface, the polarization state evolves between different linear and elliptical polarizations with varying degrees of ellipticity as a function of time. Such an approach further expands the versatility of metasurfaces and opens up new possibilities in the field of ultrafast science and technology.
[1] S. Divitt, W. Zhu, C. Zhang, H. J. Lezec, and A. Agrawal. Science 364, 890-894 (2019).

Lu Chen is a Postdoctoral Associate at the National Institute of Standards and Technology and the University of Maryland. She received a B.S. in Optical Information Science and Technology from Nankai University in 2012, and a Ph.D. in Physics from University of Pittsburgh in 2018. Her doctoral research focused on ultrafast optical response and transport properties of strontium titanate-based complex oxide nanostructures. She is currently working on ultrafast optical spectroscopy of novel nanophotonic devices including metasurfaces, metamaterials and nanoplasmonic devices.

We investigate silicon-based plasmonic devices as a platform for high-non-linear field effects at telecommunication wavelengths of 1550nm. The Silicon-based nanoplasmonic devices are fabricated on silicon-on-insulator (SOI) substrates using processing techniques that are largely CMOS compatible, thus, allowing an ease of integration with electronic and silicon photonic devices. The strong nonlinear filed confinement at the metal-Si interface allows for the generation of third harmonic (TH) 516nm radiation at unprecedented conversion efficiency that is two orders of magnitude higher than any observed to date in Silicon. This demonstrates the potential for compact visible light sources for integrated photonics or hybrid photonic-electronic nanocircuitry. We show also that electrons excited, via two photon absorption, are accelerated to energies up to several eVs by the ponderomotive potential that exists in the highly confined nanoplasmonic field. Subsequent collisions with valence electrons enable the observation of new phenomena, such as field-driven electron impact ionization, strong white light emission, and ultrafast electron-hole sweeping. These findings uncover a new strong-field interaction that can be used in sensitive nanoplasmonic modulators and hybrid plasmonic-electronic transducers.

Prof. Abdulhakem Y. Elezzabi received his B.Sc. in Physics from Brock University, St. Catharines, Canada in 1987. He received his M.Sc. and Ph.D. in Physics at the University of British Columbia, Vancouver, Canada in 1989 and 1995, respectively in Femtosecond Laser Physics. Between 1996-1997, he was IBM, Natural Sciences and Engineering Research Council of Canada & Issak Walton Killam Postdoctoral Fellow. Since 1997 he has been with the Department of Electrical and Computer Engineering at the University of Alberta. In 2003 he was appointed as a Canada Research Chair in Ultrafast Photonics and Nano-Optics at the University of Alberta. Prof. Elezzabi current research interests are in ultrafast phenomena, ultrafast physics, nanoplasmonics, high-speed photonic devices, femtosecond electron pulse generation, terahertz radiation, non-linear optics, nano-optics, laser-matter interactions, and biophotonics.

Owing to their possibilities to work as nanoscale waveguide lasers with miniaturized footprints, great material diversity and tunability, semiconductor nanowire lasers have been attracting intense attention in recent years, however, practical applications of these tiny lasers remains challenging. In this talk, I introduce our recent progress in possible routes for pushing single semiconductor nanowire lasers toward practical applications. Firstly, I introduce a wavelength-tunable single-nanowire laser with high tuning rates and excellent reversibility by incorporating temperature-dependent Varshni shift of the bandgap with ultra-low thermal inertia of a free-standing CdS nanowire. Secondly, by assembling a CdS nanowire onto the silicon nitride planar waveguide to form a Mach-Zehnder structure for mode selection, I show on-chip single-mode CdS nanowire lasers. Thirdly, I introduce a proposal to cool nanowire lasers in liquids to bestow the nanowire laser with greater versatilities.

Xin Guo received the B. S. degree in Optical Information Science and Technology from Sichuan University in 2005 and the Ph. D. degree in Optical Engineering from Zhejiang University in 2010. During 2014 and 2015, she worked as a visiting scholar in the Department of Electrical Engineering at The Hong Kong Polytechnic University. She is currently an associate professor in the College of Optical Science and Engineering at Zhejiang University. Her research interests mainly include nanophotonics and plasmonics. She has published more than 30 papers in peer-reviewed journals including Nano Letters, Accounts of Chemical Research, Laser & Photonics Reviews, Advanced Optical Materials, Optics Express.

In this talk, I will present our recent far-field and near-field investigations of quantum signatures in plasmonic systems, including the fundamental limit of electric near-field enhancement factor in one of the most common surface-enhanced Raman scattering substrates – rough metal films [1], the effects of spatial nonlocality and quantum tunneling in metallic nanoparticle dimers [2] and particle-on-film nanocavities [3], and the quantum electron transport phenomenon in plasmonic molecule junctions [4].
References:
[1] Y.D. Zhao, X. Liu et al., Nanoscale 6, 1311-1317 (2014).
[2] Q. Zhang et al., Advanced Quantum Technologies 1, 1800016 (2018).
[3] L. Lin, Q. Zhang et al., ACS Nano 12, 6492-6503 (2018).
[4] D.J. Liu, Q. Zhang et al., under revision with ACS Nano (2019).

Dangyuan Lei received his BSc, MPhil and PhD degrees all in Physics from Northwestern University, Chinese University of Hong Kong, and Imperial College London in 2005, 2007 and 2011, respectively. He is currently an associate professor with the Department of Materials Science and Engineering at City University of Hong Kong. His research interest centers on nonlinear and quantum nanophotonics and optical spectroscopy, with particular interest in surface plasmon photonics interfaced with low-dimensional materials systems. Two of his publications have been respectively selected into the RSC “Emerging Investigators” themed issue of Journal of Materials Chemistry C (2016) and the IOP “Emerging Leaders” edition of Journal of Optics (2017). Since 2007, he has published 108 journal papers, with 37 papers appeared in index>10 journals, receiving in total 3660 citations and an H-index of 38 (Google Scholar as of April 2019).

The facile laser writing approach offers a facile and powerful platform to print flat optics composed of digitalized pixels with high spatial resolution and high fidelity in a lithography-free fashion. In this paper, we report on that nano-imprints with varying geometric sizes and morphologies can be reproducibly printed by irradiation of tightly focused femtosecond pulsed beams. These nano-imprints resonantly interact with impinging light and offer tremendous flexibility in manipulating light field in amplitude and phase to realize various functionalities of interests. We demonstrate that laser splashed 3D nanostructures exhibit spectral and color tunability by illumination angle allowing the demonstration of encrypting images in angular anisotropy. Such angular anisotropy enables encrypting color images among different illumination angles when while light is employed as the source. In addition, the thermoplasmonic effect can be precisely utilized to tailor the optical properties in pre-textured Al nanostructures including their resonances and phase manipulations. Therefore, multifunctional Janus optical metasurfaces supporting color images when illuminating by white light sources and holographic images when illuminating by coherent laser beams can be realized.

Dr. Xiangping Li completed his PhD at Swinburne University of Technology in 2009. His research is focused on nanophotonic techniques for high capacity optical information technologies including optical multiplexing, plasmonics and superresolution microscopy. Dr. Li has published over 60 internationally referred journal publications including Science, Nature Photonics, and Nature Communications. He joined the Institute of Photonics Technology in Jinan University as a full professor and research leader in nanophotonic devices group in 2015.

It's an endless quest in searching for the development of laser miniaturization for different kinds of methods such as photonic crystal lasers, microdisk lasers and nanowire lasers. Utilizing the surface plasmons in replacement of photonic resonance in the laser cavity has been shown effective to down-size the cavity beyond the diffraction limit. Graphene is a membrane with thickness of only one atom and the carrier mobility can be as high as about 15000 cm2/V·s. Until now graphene has been widely used for many optoelectronics applications, for example, ultrafast photodetector, modulator, biosensor, transparent electrode and so on. As far as plasmonic laser is concerned, since the insulator layer on the metal structure is required to be very thin, it seems to be feasible to add a single-layered graphene in between the nanowire and metal while preserving the capability of forming surface plasmon polariton (SPP). Besides, we would like to take advantage of good electrical property of graphene to make a plasmonic nanolaser which can be modulated by externally applied current. By adding graphene on the insulator can form a versatile platform, called graphene-insulator-metal (GIM) structure, that can modulate the plasmonic wave characteristics. In this study, we successfully fabricated and demonstrated the SPP nanolaser on GIM structure. The improvement on the lasing threshold of ZnO nanowire on aluminum with graphene was realized.

Professor Tien-chang Lu received the B.S. degree in Electrical Engineering from National Taiwan University, Taiwan, in 1995, the M.S. degree in Electrical Engineering from University of Southern California, USA, in 1998, and the Ph.D. in Electrical Engineering and Computer Science from National Chiao Tung University, Taiwan, in 2004. He was with the Union Optronics Corporation as a Manager of Epitaxy Department in 2004. Since August 2005, he has been with National Chiao Tung University as a full-time professor in Department of Photonics. In 2007, he went to Ginzton lab, Department of Applied Physics at Stanford University as a visiting scholar. He served as the director of the Institute of Lighting and Energy Photonics, National Chiao Tung University from 2009 to 2011. From 2017, his serves as the director of Tin Ka Ping Opto-Electronics Research Center. And from 2018, he has been elected as the chairman of Department of Photonics, National Chiao Tung University.
Prof. Lu's research works includes the design, epitaxial growth, process, and characterization of optoelectronic devices. He has been engaged in the low-pressure MOCVD epitaxial technique associated with various material systems as well as the corresponding process skills. He is also interested in tailoring the light-matter interaction in micro or even nano-scale architectures, such as the microcavity, photonic crystal and plasmonic structures. Especially, Prof. Lu has been devoting to wide-gap materials and device research and has several breakthroughs, such as the first current injection blue VCSEL, photonic crystal surface emitting lasers and microcavity exciton-polariton lasers and world's smallest plasmonic nanolasers.
Prof. Lu has authored and co-authored more than 200 international journal papers. He is a recipient of The Exploration Research Award of Pan Wen Yuan Foundation 2007, Excellent Young Electronic Engineer Award 2008, Young Optical Engineering Award 2010, International Micro-Optics Conference Contribution Award 2011, Dr Ta-Yu Wu's Memorial Award 2012, Y. Z. Hsu Scientific Paper Award 2016 and Distinguished Professor of NCTU. He is an OSA Fellow since 2017, senior members of IEEE and SPIE. He also severed as deputy editor of IEEE J. Lightwave Technology and associate editors of IEEE J. Quantum Electronics.

Transparent conductive oxides are excellent plasmonic materials with their large optical nonlinearity at epsilon-near-zero (ENZ) wavelengths, which have recently emerged as candidates for design and fabrication of active nanophotonic devices. However, the physical origin of the optical nonlinearity is unclear and there is no effective physical model. We have proposed to extend the Drude model by adopting a weighted electron effective mass which takes into account the electron distribution in the nonparabolic conduction band. The relations between electron effective mass, mobility and the electron temperature are characterized by a femtosecond-pump-continuum-probe system. The extended Drude model is able to interpret the cause of the nonlinearity and provide a functional relationship between refractive index and wavelength. Both the band nonparabolicity and the temperature-dependent mobility are responsible for the intraband transition induced optical nonlinearity. The spectrally-resolved nonlinear refractive index and nonlinear susceptibilities are obtained for the first time from this model. The results can be applied to help in the design and modeling of spectral responses of nonlinear plasmonic devices.

Ting Mei is a distinguished professor of School of Science, Northwestern Polytechnical University. He received his Bachelor's and Master's Degrees in Optical Engineering from Zhejiang University and Ph.D. Degree in Electrical Engineering from the National University of Singapore. He was the Director of the Institute of Optoelectronic Materials and Technology, South China Normal University and an Associate Professor with tenure in Nanyang Technological University, Singapore. His research is in the fields of surface plasmonics and semiconductor optoelectronics. He is a senior member of IEEE and served as Vice President of IEEE-LEOS/Photonics Society Singapore Chapter for 2004 and 2005 and a member of IEEE EDS Optoelectronic Devices Committee since 2014. He is a board member of council, China Optical Engineering Society. He chaired/cochaired the 2nd and the 4th OSA topical conferences of Advances in Optoelectronics and Micro/nano-optics (AOM). He is a member of the editorial board of Advanced Photonics.

Two-dimensional highly luminescent CsPb2Br5 has been reported for optoelectronic applications in recent years. However, the band gap and the origin of green photoluminescence (PL) are still in intense debate. To reveal the completed optical properties of the CsPb2X5 (X=Br, Cl, or I) proveskites and end these controversies, both PL-inactive and green emission CsPb2Br5 are synthesized by using different solution methods. Same-spot Raman-PL spectra, which is a kind of effective probe technique characterized by the strong correlation between structure property, reveal that CsPbBr3 nanocrystals are the origin of the green emission. The Raman-PL spectra under applied hydrostatic pressure with a diamond anvil cell rule out the alternative luminescence theory of defect states such as Br vacancies. Pressure-dependent absorption indicates that the bandgap of CsPb2Br5 is 3.45 eV, which is 0.3-0.4 eV higher than that of those pervious reports and agrees well with our density functional theory (DFT) calculation, and this bandgap value remains nearly constant with pressure up to 2 GPa. We further prove that the luminescence of the CsPbBr3-xXx (X = Cl or I) nanocrystals is responsible for the light emission of their corresponding CsPb2Br5-xXx. Our findings open up new opportunities to understand and develop highly efficient inorganic lead halide optoelectronic devices.

Wang Chong, obtained his Ph.D. in solid electronics and microelectronics in 2007 from Shanghai Institute of Technical Physics, Chinese Academy of Science (CAS), then joined Yunnan University as an associated professor. He did one-year research at University of Houston in USA as a visiting scholar (in 2017), and built a solid partnership with Prof. Jiming Bao. Now, he is a professor and Master's supervisor of Materials Science at Yunnan University, and have been elected a Member of Youth Committee of Chinese Materials Research Society (CMRS) for his contribution on the low dimensional semiconductors and their application on the photodetectors and light emitting diodes (LEDs). In recent years, his research work is financially supported by the National Science foundation of China, the Reserve Talents of Academic and Technical Leader Project, and Ten Thousand Talents Plan of Yunnan Province, China. He had published over 100 paper, his representative paper was published on Advanced Materials, Chemical Communications, Optics Express, Applied Surface Science, and Nanotechnology, and has been cited over 900 times.

Metal nanostructures can concentrate electromagnetic energy into nanoscale volumes due to the excitation of surface plasmons, enabling the manipulation of light beyond the diffraction limit. Nanowires supporting propagating surface plasmons can function as nanowaveguides to realize light guiding with subwavelength field confinement, providing a fundamental building block for nanophotonic integrated circuits. In this talk, I will present our studies on the propagating surface plasmons on metal nanowires and their interaction with excitons in quantum emitters.

Hong Wei is a professor in Institute of Physics, Chinese Academy of Sciences. She received her B.S. in physics from Shandong University, China, in 2004, and her Ph.D. from Institute of Physics, Chinese Academy of Sciences, in 2009. Her research is focused on plasmonics and nanophotonics. She did innovative work on surface plasmon propagation in metal nanowires, nanowire-based plasmonic devices, and interconversion of nanowire plasmons with excitons at single quanta level. She is author of more than 50 papers, has been cited more than 2500 times, and has presented more than 50 invited talks. She is a member of the editorial board of Journal of Optics, and a topical editor of Journal of the Optical Society of America B.

The ability to fabricate high-performance photonic devices, e.g. lasers, directly on silicon substrates would enable the long-pursuit efficient light sources for the silicon photonics. However, large material dissimilarity between III-V materials and silicon, especially polar versus nonpolar surfaces and lattice mismatch, makes the monolithic growth of III-Vs directly on silicon substrates highly challenging by introducing high-density antiphase boundaries and threading dislocations. Recently, III-V quantum dot devices have received much attention for integrated III-V/Si photonics due to their unique properties, in particular reduced sensitivity to defects and delta-function density of states. Here, recent advances in fabricating optoelectronic devices based on high-quality III-V heterostructures directly on silicon substrates are introduced.

Dr. Jiang Wu is a Professor of the Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China (UESTC). Dr. Wu received his PhD degree in Electrical Engineering from the University of Arkansas-Fayetteville in 2011. After his PhD, he joined UESTC as an Associate Professor and then Professor. He joined the Photonics group at University College London (UCL) as a Research Associate in 2012. From 2015, he was a Lecturer at UCL and a Key Principle Investigator of the UK EPSRC Future Compound Semiconductor Manufacturing Hub. In 2018, he returned to UESTC as a professor and currently his research interests include Molecular Beam Epitaxy of III-V semiconductors and optoelectronic devices, especially infrared photodetectors and light-emitters. He has co-authored over 100 technical papers in Nat. Photonics, Sci. Adv., Nano Lett., Adv. Mater., etc. He has delivered over ten invited seminars and invited talks at international conferences, including PIERS, SPIE, etc. He is a Fellow of Higher Education Academy and Senior Member of IEEE. He serves as the Editor-in-Chief of Nanoscale Research Letters, Associate Editor of IEEE Access, and Editorial Board Member of Scientific Reports, Nano-Micro Lett., and Experiment Science and Technology.

Dopants induced electric fields and their influence on the band-edge absorption coefficient of GaN are theoretically examined. For dopants induced electric field distribution, it is derived with Bayes' rule. For the average electric field strength, it is revealed to be quite strong, e.g., in an order of 106 V/m in GaN with a fairly low dopant density. On the basis of Franz-Keldysh mechanism, influence of the dopants induced electric fields on the band-edge absorption coefficient of GaN is then investigated. Without any adjustable parameters, absorption coefficients of GaN are computed and are in good agreement with available experimental values.

S. J. Xu is currently a professor with tenure in Department of Physics, The University of Hong Kong, China. He received his PhD degree in Electronic Engineering from Xi'an Jiaotong University in 1993. He has authored >170 peer-reviewed articles and letters with >4600 SCI citations.

We report on high-resolution photocurrent (PC) spectroscopies of a single self-assembled InAs/GaAs quantum dot (QD) embedded in an n-i-Schottky device with an applied magnetic field. When the magnetic field is applied in Voigt geometry, the mixture of bright and dark states results in an observation of dark exciton states. For a positive charged trions (X+) in a single quantum dot, giant enhancement of photocurrent has been achieved because of the Coulomb repulsion between the two holes.
In addition, photonic crystal cavities with high quality factors around 10000 are fabricated with single quantum dots located in antinode position of the cavity. Strong coupling for cavity QED between different excitonic states in a single quantum dot and the cavity will be presented, two-photon Rabi splitting in a strongly coupled cavity-dot system is demonstrated. Both exciton and biexciton transitions couple to a high quality factor photonic crystal cavity with large coupling strengths over 130 μeV. When the cavity to simultaneously couple with two exciton states, two-photon Rabi splitting between biexciton and cavity is achieved, which can be well reproduced by theoretical calculations with quantum master equations.
Finally, strong interactions between cavities and p-shell excitons with a great enhancement by the in situ wave-function control will be demonstrated because of the large wave-function extents and nonlocal interactions beyond the dipole approximation. A large coupling strength of 210 μeV has been achieved, indicating the great potential of p-shell excitons for coherent information exchange.

Dr Xiulai Xu received BA degree in Electronic Engineering from the Jilin University in 1996, and Ph.D. degree from Cavendish Laboratory, University of Cambridge in 2005. He has been working as research scientist, senior research scientist in Hitachi Cambridge Laboratory from 2005-2011, and was also a research fellow in Clare Hall, University of Cambridge during 2009-2011. He is currently a professor with Institute of Physics, Chinese Academy of Sciences on quantum optoelectronics and nano-photonics.

Owing to the advancement in new material design over the past few years, the power conversion efficiencies (PCE) of polymer solar cells have now reached over 15% and 17% for single-junction and multi-junction devices, respectively. However, in order the meet the commercialization requirement, further improvement in device stability and the exploration of niche applications of polymer solar cells are urgently needed. In this talk, I will discuss how to utilize an integrated strategy combining material design, interface engineering and optical management to tackle the efficiency, stability and application issues of polymer solar cells. I will particularly highlight our work on using optical management as a powerful means to enhance the performance of polymer solar cells by maximizing the light harvesting property of the devices. The capability to use optical model to precisely predict the light propagation property and charge generation rate within the devices allows us to design optimal device architectures with improved performance and stability. I will also discuss how to apply high throughput optical model to rapidly screen more than 10 million device structures in order to identify the very best device design for extremely high performance tandem and semitransparent polymer solar cells (ST-PSCs). In addition, I will also discuss how to engineer the optical property of ST-PSC for greenhouse applications. Finally, a multiple-function semitransparent polymer solar cell with both heat insulation and power generation properties will also be presented.

Hin-Lap (Angus) Yip is a Professor in the State Key Laboratory of Luminescent Materials and Devices and the Materials Science and Engineering (MSE) Department in South China University of Technology (SCUT). He got his BSc and MPhil degrees in Materials Science from the Chinese University of Hong Kong, and completed his PhD degree in MSE in 2008 under the guidance of Prof. Alex Jen at the University of Washington, Seattle. He joined SCUT in 2013 as full Professor. His current research focuses on the use of an integrated approach combining materials, interface, and device engineering to improve both polymer and perovskite optoelectronic devices. He had published more than 160 scientific papers with citations ~ 16000 and H-index of 69. He was also honored as “Highly Cited Researcher” in Materials Science by Thomson Reuters from 2014-2018.

The integration of monolayer transition metal dichalcogenides (TMDs) and plasmonic nanocavities merges the advantage of the two continents, i.e., the excellent optoelectronic properties of TMDs and the extreme light concentration of the plasmonic nanostructures. In this talk, I will talk about how to integrate monolayer TMDs with deep subwavelength nanocavities, to realize the strong, intermediate or weak coupling of plasmons and excitons. In the strong coupling region, we observed Rabi splitting from the nanorod plasmon and excitons in 1L WSe2. In the intermediate coupling region, we observed a 1700-times photoluminescence enhancement inside the hot spot, which is the direct consequence of the energy transfer from plasmon to excitons. In the weak coupling region, we used 1L MoS2 as atomic lattice probe to measure the plasmonic field enhancement by surface enhanced Raman scattering, revealing the onset of quantum tunneling process at sub-nanometer gap.

Shunping Zhang received his Bachelor's degree from Sun Yat-Sen University in 2008 and obtained his Pd. D. degree from Institute of Physics, Chinese Academy of Sciences in January, 2013. He joined Wuhan University first as an outstanding postdoc and then got promoted as an associate professor in April, 2015. He has published more than 30 peer reviewed papers (> 2000 citations in Web of Science), including PRL, Nature Commun., Nano Lett. Light: Sci. & Appl. etc. His major achievements include the discovery of chiral surface plasmon polaritons, ultrasensitive plasmonic sensing based on Fano resonances or cavity plasmons, and strong coupling of plasmon and 2D excitons.

Chalcogenide phase change materials based on germanium-antimony-tellurides (GST) have shown outstanding properties in resistive random-access memory (PRAM). They could provide reversible phase transition, a high degree of scalability, low power consumption, and multi-level storage capability. The reversible phase change between the amorphous and crystalline states could be triggered by thermal, optical or electrical pulses as long as the generated heat raises the temperature of GST above the crystallization or melting point. The process is non-volatile and thus no power is required to maintain the state. Besides the electrical resistance change, a pronounced change also occurs in optical property, namely the complex refractive index of GST, during the phase transition. In this talk, we will review our recent progress on silicon-GST hybrid photonic devices for non-volatile optical signal manipulation. In particular, we demonstrate a photonic memristive switch element composed of a silicon MMI structure with a nanoscale GST patch on top. The phase change is triggered by applying an electrical pulse to the silicon resistive heater. The maximum transmission contrast can exceed 20 dB and multiple intermediate transmission levels can be obtained by partial crystallization of GST. GST can also be integrated into a ring resonator to control the resonance extinction ratio. Transmission contrast of larger than 20 dB is obtained when the GST phase transition is triggered by using a sequence of optical pulses launched from the input waveguide.

Dr. Linjie Zhou received his B.S. degree in microelectronics from Peking University in 2003. He received his Ph.D. degree in electronic and computer engineering from the Hong Kong University of Science and Technology in 2007. From 2007 to 2009, he worked as a postdoctoral researcher at University of California, Davis. Currently, he is a professor in the State Key Lab of Advanced Optical Communication Systems and Networks of Shanghai Jiao Tong University. His research interests include silicon photonics, plasmonic devices, and optical integration. He has published more than 200 peer-reviewed journal and conference papers with over 2000 citations and has given more than 50 invited talks in international and domestic conferences. He has organized many sessions at multiple international and domestic conferences. He was elected as the “Yangtse Rive Young Scholar” by the Minister of Education of China in 2016. He was granted the “Newton Advanced Fellowship” in 2016 and “National Science Fund of China for Excellent Young Scholars” in 2014 and entered the “Shanghai Rising-Star Program” in 2014. He also got the SMC Excellent Young Faculty Award of Shanghai Jiao Tong University in 2014 and 2010.

One-electron approximation and hybrid functionals based density functional theory wrongly describe the reduced charge screening and the enhanced electron–electron correlation in the low-dimensional (2D) systems. Thus many-Body perturbation theory calculations (GW + Bethe-Salpeter equation) are utilized to describe such couplings and to correct electronic and optical properties in nano-systems. I will present the theory of this method and apply it to novel two-dimensional materials, including siligraphene, halogenated TiN and Sc-based Mxene. These modeling results can guide future development of 2D materials for optoelectronic applications .

Dr. Liujiang Zhou received his Ph.D. in 2014 from University of Chinese Academy of Sciences and performed postdoctoral researches at University of Bremen, Germany (2014.10-2016.12) and at Los Alamos National Laboratory, USA (2017.1-2019.5). He started his own independent academic career as a full professor at University of Electronic Science and Technology of China. His research efforts are focused on information functional materials, optoelectronic devices and computational materials, etc. He utilizes methods of first principle calculations (such as DFT, TD-DFT, GW), semi-empirical (phase-field, etc.) and molecular dynamics, etc., to conduct the computational designs on novel optoelectronic, energy, topological materials, and to carry out static and dynamic simulations on electronic, magnetic, phonon, optical and intersecting properties.