I will review the physical properties of a new generation of artificial photonic materials and metamaterials with optical properties not found in nature. We begin with the realization of pseudospin-1 physics using dielectric photonic crystals. We show some physical implications of the photonic crystals exhibiting an accidental degeneracy induced conical dispersion at k=0, such as the realization of zero refractive index medium. The photonic states of such photonic crystals near the Dirac-like point can be described by an effective spin-orbit Hamiltonian of pseudospin 1. The transport of waves in pseudospin-1 systems exhibits many interesting phenomena, including super Klein tunneling, robust super-collimation and unconventional Anderson localization. We will then discuss the properties of a new type of metamaterials whose properties are determined the connectivity of a network structure, not by the resonances of individual elements within a unit cell. Such metamaterials cannot be described using local effective parameters, although the unit cell is deep subwavelength. In contrast to natural materials which have their index ellipsoids centered at k=0, the non-resonant metamaterial can possess multiple index ellipsoids centered at arbitrary nonzero k-points. Such metamaterials can be used to design broadband devices.

C.T. Chan received his PhD degree from the University of California at Berkeley in 1985. He is currently Daniel C K Yu Professor of Science, Chair Professor of Physics at HKUST, the Director of Center for Metamaterial Research and the Director of Research Office of HKUST. He has been elected a Fellow of the American Physical Society and Hong Kong Physical Society. He received the Achievement in Asia Award of the Overseas Chinese Physics Association (2000) and Croucher Senior Research Fellowship (2010). He is a co-recipient of Brillouin Medal for his research in phononic metamaterials (2013). His primary research interest is the theory and simulation of material properties.

Information metasurfaces are described by digital elements 0 and 1 with the opposite electromagnetic (EM) responses (e.g. anti-phases), instead of by the effective medium parameters. By designing different coding states of the digital elements, the EM waves can be controlled by the information metasurfaces in the desired way. We have shown that, when digital coding metasurfaces are space-encoded, the spatial-wave fields and beams can be manipulated in programmable manner; when the digital metasurfaces are time-encoded, the frequency spectra of EM waves (e.g. harmonics and their power distributions) can be manipulated. With space-time digital coding, the information metasurfaces attain simultaneous manipulation of EM waves in both space and frequency domains. The information metasurfaces set up a bridge between the physical world and digital world, and hence could produce new information systems. As relevant applications, I report several new imaging systems and novel architectures of wireless communication systems based on the information metasurfaces. In the new architectures, the traditional modules of analog-digital converter, mixers, filters, and amplifiers are no longer needed. The proposed method will have more impacts to the future information technologies.

Tie Jun Cui is the Chief Professor of Southeast University, Nanjing, China. He authored two books and published over 400 peer-review journal papers, which have been cited by more than 24000 times (H-Factor 77, from Google Scholar). Dr. Cui received the Natural Science Award (First Class) from Ministry of Education, China, in 2011, and the National Natural Science Awards (Second Class) in 2014 and 2018, respectively. His researches have been selected as one of the “10 Breakthroughs of China Science in 2010”, “Best of 2010” in New Journal of Physics, and “Optics in 2016” by OSA, and has been reported by Nature News, MIT Technology Review, Scientific American, Discover, New Scientists, etc. Dr. Cui is an IEEE Fellow.

Manipulating the topological property of iso-frequency contour (IFC) from a closed ellipsoid to an open hyperboloid will provide a unique control for the interaction between light and matter. In this talk, I will discuss our recent studies on manipulation of light by topological tuning of IFC in the following two examples:
(1) Light emission control by topological tuning of IFC. Based on metamaterials made of transmission lines, we experimentally demonstrate the magnetic topological transition of dispersion in anisotropic two-dimensional metamaterials. Different emission patterns from a point source are observed in microwave experiments as the result of the topological transition.
(2) Band gap control by topological tuning of IFC. A mechanism for dispersion control of band gap is proposed based on phase compensation effect between hyperbolic and elliptic structures. Band gap with designed properties, such as blue or red shift, and even invariant of the band gap with the incident angles, are realized in 1-D stacked structures consisted of hyperbolic and elliptic materials.

Hong Chen, distinguished professor in the school of physics science and engineering at Tongji University. He received his B.Sc. degree in physics from Fudan University in 1982 and Ph.D. degree in condensed matter physics from Shanghai Jiaotong University in 1986. His research interests include photonic crystals, metamaterials, plasmonics, and artificial microstructures for manipulation of classical and quantum waves. For his work, Hong Chen has received several awards. In 1997 he received the Outstanding Young Scientist Award from National Nature Science Foundation of China and in 1999 he received the National Award for Natural Sciences by the State Council of China.

The concept of an invisibility cloak is a fixture of science fiction, fantasy, and the collective imagination. Here I will review the recent experimental progress in invisibility cloaks. In particular, I will discuss the experimental realization of a remote cloaking device that makes any object located at a certain distance invisible at direct current frequency, a 3D cloak that functions for plain sight at optical frequency, and broad band surface wave cloaks.

Dr. Hongsheng Chen received the Ph.D. degree from Zhejiang University in 2005. He is currently a Chang Jiang Scholar distinguished professor in the Electromagnetics Academy at Zhejiang University in Hangzhou, Zhejiang, China. He was a Visiting Scientist (2006-2008), and a Visiting Professor (2013-2014) with the Research Laboratory of Electronics at Massachusetts Institute of Technology, USA. He is the Vice-Dean of the College of Information Science and Electronic Engineering, Zhejiang University. He is the coauthor of more than 200 international refereed journal papers. He serves on the Topical Editor of Journal of Optics, the Editorial Board of the Scientific Reports, and Progress in Electromagnetics Research. His current research interests are in the areas of metamaterials, invisibility cloaking, transformation optics, and theoretical and numerical methods of electromagnetics.

In this talk, we will share some of our recent experiments on Transformation Optics. In particular, a self-focusing lens and a multimode waveguide crossing based on conformal mappings; a geodesic lens and a topological deflector based on curved surfaces; a field concentrator based on Fabry-Pérot resonances.

Huanyang Chen received the B.Sc. and Ph.D. degrees in physics from Shanghai Jiao Tong University, Shanghai, China, in 2005 and 2008 respectively. From 2006 to 2009, he was a Research Assistant and a Postdoctoral Fellow in the Hong Kong University of Science and Technology, Hong Kong. He was a Professor in Soochow University from 2009 to 2016 and in Xiamen University since 2016. His research covers photonic/photonic crystals, metamaterial designs, and transformation optics/acoustics. He has authored or coauthored more than 100 papers. His papers have been cited for more than 5000 times, and he has an H-index of 35.

The discovery of topological photonics provides a new degree of freedom to control the flow of light, enabling novel optoelectronic functionalities and devices in silicon-on-insulator (SOI) platform. However, the subwavelength strategy at micro-nano scale remains challenge. Recent developments of valley photonic crystals pave an alternative way to achieve SOI topological nanophotonic devices with high performance. We have a theoretical proposal on all-dielectric valley photonic crystals (VPCs) with nonzero valley Chern number by employing valley degree of freedom, as well as turn such proposal VPCs into reality by using all-dielectric rods at microwave region. Recently, we have realized a VPC in a silicon wafer on the top of silicon dioxide substrate, i.e. SOI slab. Valley-dependent topological edge states operate below the light cone so that the photonic crystal slab can strongly confine the propagating waves in the plane of chip. Benefit from near-quarter-wavelength periodicity, our VPC can develop a high-performance topological photonic device with a compact feature size. We have fabricated flat-, Z- and Omega-shape topological channels and measured their flat-top high-transmittance spectra with relatively large bandwidth. Such phenomena give evidences for the observation of robust transport at telecommunication wavelength. Finally, we have experimentally demonstrated on-chip topological photonic routing, based on the VPC chiral channel. With introducing a subwavelength microdisk to serve as phase vortex generator, the valley-chirality-locked edge state is selectively excited. The work shows a prototype of on-chip photonic devices based on topological modes and photonic analog of quantum information processing.

Jian-Wen DONG, NSFC Excellent Young Scientists, Cheung Kong Scholar Youth Professor, is now the Professor in Sun Yat-sen University, Guangzhou, China. Research of the Dong group focuses on the fundamental physics and optical information applications of topological photonics, nanophotonics, photonic crystal and metasurface. Dr. Dong has published several original works in high impact journals including Nature Materials, Physical Review Letters, Nature Communications, two of which are selected as ESI highly-cited papers, and the "top ten progress of Chinese optics in 2017 - basic research”.

Metal nanostructures are plasmonic optical resonators which can store electromagnetic energy at the localized plasmonic resonance modes. To utilize localized surface plasmon resonance, various surface plasmon resonance sensors have been proposed and investigated. However, these surface plasmon resonance sensors rely on optical spectrometers for localized surface plasmon resonance measurement. In this talk, I will present a new surface plasmon resonance sensor platform based on super-period metallic nano-gratings. The new plasmonic sensor platform can measure localized surface plasmon resonance without using optical spectrometers. Additionally, optical filters based on metal thin film structures will be discussed in this talk.

Junpeng Guo received a Ph.D. degree from the University of Illinois at Urbana-Champaign and a Bachelor of Science degree from the Peking University, Beijing. He started his career as a Research Scientist with the Rockwell International Science Center in Thousand Oaks, California and later joined the Sandia National Laboratories in Albuquerque, New Mexico. He joined the faculty as a Professor of Electrical Engineering and Optics at the University of Alabama in Huntsville in 2005. Prof. Guo is a Fellow of the International Society for Optics and Photonics. He currently serves as an Associate Editor of Photonics Research and also serves as an Associate Editor of Journal of Nanophotonics. His areas of research are nanophotonics, plasmonics, and metamaterials devices for biosensors, optical filters, and solar energy harvesting.

Metamaterials are often described by effective media with unusual effective parameters. Due to the deep sub-wavelength scale of the metamaterial structures, the effective parameters of metamaterials usually do not have spatial dispersion. However, when the structure is at the wavelength scale, spatial dispersion emerges in metamaterials. In this talk, I will demonstrate a new type of pseudo-local metamaterials which exhibits both frequency and spatial dispersions. Interestingly, under some circumstances, such metamaterials behaves exactly like the local media and can be described by extraordinary parameters that are difficult to realize in the standard metamaterial approach. While in some other cases, the unique feature of nonlocality can enable some extraordinary applications that are not possible by traditional metamaterials as local effective media.

Prof. Yun Lai obtained his PhD degree in physics in Hong Kong University of Science and Technology (HKUST) in 2005. He worked as a research associate in HKUST from 2005-2011 and a professor in Soochow University from 2011-2017. Prof. Lai has joined the school of physics in Nanjing University since 2018. Prof. Lai proposed various concepts and theories in metamaterials, such as illusion optics, double zero media, ultratransparent media, hybrid elastic solids, percolation of light, hybrid cloaks, etc. He has published more than 60 peer-reviewed papers on SCI journals, including 2 on Nature Materials, 7 on Physical Review Letters/X, 2 on Nature Communications, etc. Total citation number exceeds 2000. Some findings were reported by Science、Nature、Nature Materials、Discovery Channel, etc. Prof. Lai was enrolled in the first patch of Thousand Youth Talents Program in China.

The vacuum Rabi splitting, which stems from a single photon interaction with a quantum emitter (a single atom, molecule, or quantum dot), is a fundamental quantum phenomenon. Intrinsically this effect is reflected in the internal energy splitting of quantum emitter state, while extrinsically it is reflected by the spectral splitting in either photoluminescence, or fluorescence, or scattering, or absorption spectrum. Many reports have claimed that using J-aggregates coupling to highly localized plasmon can produce giant Rabi splitting (in scattering spectra) which is proportional to √N, where N is the number of excitons in J-aggregates, and this splitting originate purely from quantum interaction between excitons and plasmons. In this work we show that compared with the fluorescence which is a sign of molecular internal states and can really reflect the molecular energy-level splitting, the scattering spectra is far sensitive to the surrounding matter. The giant spectral splitting stems both from the quantum interaction of single-molecule with plasmons (Rabi splitting) and from the classical optical interaction of multiple molecules with plasmons. We develop a Lorentzian model to describe molecules and plasmon and find that collective optical interaction is dominant to generate the giant splitting (in scattering spectra), which is also proportional to √N, upon the quantum interaction of single-molecule Rabi splitting. Simply speaking, the observed giant spectral splitting is not a pure quantum Rabi splitting effect, but rather a mixture contribution from the large spectral modulation by the collective optical interaction of all molecules with plasmons and the modest quantum Rabi splitting of single-molecule strongly coupled with plasmons.

Prof. Zhi-Yuan Li is a professor in College of Physics and Optoelectronics, South China University of Technology, Guangzhou. Before this he worked in Institute of Physics, CAS Beijing as a principal investigator. Prof. Li’s research interests include theory, experiment, and application of photonic crystals, nonlinear and ultrafast optics, plasmonics, optical tweezers, quantum optics, and quantum physics. He is the author or coauthor of more than 400 peer-reviewed papers in physics, optics, chemistry, and materials science journals. These papers have been cited by about 21,000 times. He serves as a Co-Editor of EPL and the editorial board member of Acta Optica Sinica, and Advanced Optical Materials. He has presented over 100 invited talks in international and domestic conferences.

Some interesting phenomena and novel devices are arising by having free electrons interact with various nano-structures. Here we demonstrate the first on-chip integrated free electron light source by greatly decreasing the electron energy for generating Cherenkov radiation (CR), the Smith-Purcell radiation (SPR) in deep UV region by passing an electron beam through a nano-slot of grating, and the free electron excited SPASER by passing an electron beam over a plasmonic cavity. The work opens up the possibility of exploring high performance on-chip integrated free electron light source and optoelectronic devices, and provides a way for realizing integrated free electron laser in ultraviolet frequency region.

Fang LIU was born in 1980. He received the B.S.degree from Beijing Institute of Technology, China, in 2003, and Ph. D degree from Tsinghua University, China, in 2008. In July 2008, he joined the Electronic Engineering Department, Tsinghua University, China, and was promoted as an Associate Professor and Specially Appointed Researcher in Dec. 2011 and Feb. 2016, respectively. In 2015, he was a visiting scholar in the Electrical Engineering and Computer Science Department, University of California, Berkeley, USA.
His current research interests is plasmonic optoelectronic devices and their applications. He published about 90 peer-review journal papers, which was cited by more than 700 times. He proposed and realized the hybrid plasmonic-dielectric coupler, integrated plasmonic bio-sensor, plasmonic metal nanoparticle enhanced thin-film solar cells, and two surface-plasmon-polariton absorption based nano-lithography, which were published by Applied Physics Letters, Sensors and Actuators B, Scientific Reports, and Optics Express. Recently, he demonstrated for the first time the threshold-less Cherenkov radiation and realized the first on-chip free-electron light source in the world. The paper was published as the “home-page paper” by Nature Photonics in May, 2017. In the same issue, a news/views paper “A low-energy Cherenkov glow” reported his achievements and commented. This work was selected as “10 Breakthroughs of China Optics in 2017”.

The notion of synthetic dimensions has been expanded the realm of topological physics to four dimensional (4D) space lately. In this work, non-Hermiticity is used as a synthetic parameter in PT-symmetric photonic crystals to study the topological physics in 4D non-Hermitian synthetic parameter space. We realize a 3D exceptional hypersurface (EHS) in such 4D parameter space, and the degeneracy points emerge due to the symmetry of synthetic parameters. We further demonstrate the existence of exceptional degenerate points (EDPs) on the EHS that originates from the chirality of exceptional points (EPs), and the exceptional surface near EDPs behaves like a Dirac cone. We further show that a very narrow reflection plateau can be found near these EDPs, and their sensitivity towards the PT-symmetry breaking environmental perturbation can make these degeneracy points useful in optical sensing and many other nonlinear and quantum optical applications.

Hui Liu, Professor at Nanjing University, Associate director of National Key Laboratory of Solid State Microstructures. National Science Foundation for Outstanding Young Talents of China. Hui Liu received his Ph.D. in 2003 from Department of Physics, Nanjing University in China. In 2004-2005 he did postdoctoral research at University of California at Berkeley. Since 2006, he is a professor of physics at Nanjing University in China. His research interest includes optical metamaterials, transformation optics, and curved space-time in photonic chips. He has published over 70 SCI papers, including Nature Photonics, Nature Communications, Phys. Rev. Lett, etc. He has taken charge of several national projects, including "863" key projects and NSFC projects.

Controlling light is the dream of scientists for centuries. Transformation optics offers a possible route to this dream. It provides a picture that is as intuitive as the ray optics but is exact at level of Maxwell’s equations, and therefore can be applied to light control at any length scale. However, the designs of ideal transformation optical devices require three-dimensional and inhomogeneous metamaterials, which are extremely difficult if not impossible to realize with traditional approaches. These problems hinder the realizations of ideal transformation optical devices for decades. In this talk, I’ll first give an overview of recent progress in transformation optics, and then summarize existing problems in this field, and finally show that the ‘photonic doping’ approach enables a powerful platform to realize ideal transformation optical devices. A number of examples, such as ideal ultrathin retroreflector, flat magnified superlens, and ideal omnidirectional invisibility cloak, are realized with this approach.

Yu Luo received the B.E. degree in Electronic & Information Engineering from Zhejiang University, China, in 2006, and Ph.D. in physics from Imperial College London, UK, in 2012. He then remained in Imperial College London as a research associate after graduation. In 2015, he joined the School of Electrical and Electronic Engineering, Nanyang Technological University, as an assistant professor. Luo’s research interests focus on metamaterials and plasmonics ranging from the design of invisibility cloaks and plasmonic light-harvesting devices to the study of nonlocal and quantum phenomena in mesoscopic plasmonic systems. He has published more than 90 international refereed journal papers which have received over 3000 citations.

Objects with nonzero temperature will radiate thermal energy. Consider the fact that heat is almost the last energy outlet for a physical or chemical interaction process and the waste heat energy may exist anywhere. It shall a very interesting and also important topic if we can collect and recycle the waste heat. Thermal radiation provides a possible way for this purpose. In this talk, we will show that the key factor, i.e., the radiation efficiency, could be substantially enhanced in the near-field case where two objects have a distance far smaller than the thermal wavelength. We carry out such an experimental utilizing the plasmonic coupling between two graphene sheets. A large super-Planckian thermal radiation efficiency 4.5 times larger than the blackbody limit is obtained at a vacuum gap of 430 nm. The influence of the Fermi level of graphene is discussed both theoretically and experimentally. We also indicate that the Schottky junction formed at the Gr-Si interface may play a vital role in transforming the collected heat into useful electric energy via a near-field thermophotovoltaic (TPV) cell. In the end, I will also would like to introduce our recent interesting results on the daytime passive radiative cooling.

Yungui MA, Professor, College of Optical Science and Engineering, Zhejiang University, selected by the New Century Outstanding Youth Talents Program of the Ministry of Education in 2011. He received the Bachelor degree (physics) in 2000 and doctoral degree (physics) in 2005 from Lanzhou University (China). He worked in National University of Singapore from 2005 to 2010 as a Research Fellow and later as a Research Scientist and joined in Zhejiang University from 2011. He has worked more than 10 years in the field of metamaterial/sub-wavelength optics and published more than 80 SCI papers in journals including Nature Materials, Physical Review Letters, Nature Communications, etc. He received the first prize in natural science research of Zhejiang Province in 2018 and currently he serves as the editorial committee member of the journal “Progress in Electromagnetics Rsearch Letter—PIER”.

Recently, tunable nanophotonic devices have drawn intense attention with great promise for practical applications. In this work, we have experimentally demonstrated several dynamically-tunable plasmonic devices based on phase transition of vanadium dioxide, which include dynamic plasmonic color generators, dynamically switchable polarizers, and dynamically tunable bowtie nanoantennas. We have fabricated periodic arrays of silver-nanodisks on a vanadium dioxide film to realize different colors, relying on the excitation of localized and propagating surface plasmons. Based on insulator-metal transition of vanadium dioxide, the plasmonic colors can be actively tuned by varying temperature. This approach of dynamic color generation can easily realize diverse color patterns, which makes it beneficial for display and imaging technology. We have also designed a system consisting of anisotropic plasmonic nanostructures with vanadium dioxide that exhibits distinct reflections subjected to different linearly polarized incidence at room temperature and in the heated state. The composite structure can thus be used to realize a dynamically switchable infrared image, wherein a pattern can be visualized at room temperature, while it disappears above the phase transition temperature. Besides, we have made the dynamically tunable bowtie nanoantennas integrated on a vanadium dioxide thin film. The investigations here can be applied in dynamic digital displays, optical data storage, and imaging sensors.

Professor Ruwen Peng received her BS, MS and Ph.D. degrees in condensed matter physics from Nanjing University in 1989, 1992, and 1998, respectively. Currently she is a distinguished professor in Nanjing University and a principal investigator at National Laboratory of Solid State Microstructures. She was honored the Chinese Young Women Scientists' Award in 2011, and Xie Xide Award in 2013. Her current research interests include plasmonics and nanophotonics, metamaterials, photonic quasicrystals, phononic transport and heat transfer in nanostructures.

Engineering thermal emission of objects enables versatile applications. In the last two decades, the emerging field of nanophtonics has offered unprecedented solutions—that are impossible with conventional approaches—to engineer thermal emission by controlling the emissivity of objects with nanostructures on object surfaces. In this talk, we report our recent research efforts in delivering novel nanophotonic-designed thermal emitters, focusing on the applications in thermal camouflage and thermal management of human bodies.

Min Qiu received B.Sc. degree (1995) and Ph.D. degree (1999) in Physics, both from Zhejiang University, China, and Ph.D. degree (2001) in Electromagnetic Theory from Royal Institute of Technology (KTH), Sweden. He joined KTH as an assistant professor in 2001 and became Professor of Photonics in 2009. He moved to Zhejiang University, China, in 2011. Since 2018, he is the Chair Professor of Photonics and Vice President for Research, Westlake University, China. His research interests include nanofabrication technology, nanophotonics, and green photonics.

Photonic graphene, the photonic analog of graphene constructed with waveguide arrays arranged in honeycomb lattice (HCL) geometry, has provided a useful platform to emulate graphene physics and topological phenomena that would otherwise be inaccessible in real graphene. In recent studies, artificial HCLs have been successfully employed to investigate a variety of fundamental phenomena such as strong sublattice symmetry breaking, strain-induced pseudomagnetic fields, Berry curvature effects and photonic topological insulators. Pseudospin, inherent sublattice degree of freedom, is commonly considered as only a mathematical analogy with electron spin, but recent theoretical studies and experimental observations suggested that pseudospin is also gifted with a real angular momentum. In this talk I will present some of our recent work related to pseudospin-mediated vortex phenomena arising from pseudospin to orbital angular momentum conversion in photonic graphene, including pseudospin dependent vortex generation, topological charge flipping and topological charge transformation. Moreover, the valley vortex states and degeneracy lifting related to the valley degree of freedom in momentum space will also be discussed.

Daohong Song is an associated professor at school of Physics, Nankai University. He received his B.S and P.H.D degree from Nankai University in 2004 and 2009, respectively. His current research interests focuses on novel optical phenomena in Dirac-like periodic structures. He has published many papers in prestigious journals including Nature Materials, Nature Communications, and Physical Review Letters.

1.3-μm surface-emitting lasers are key devices for long distance optical interconnects. However, presently the low output power of several milliwatts limits their application. In this study, by introducing a special two-dimensional photonic-crystal and using InAs quantum dots as active material, a continuous-wave output power of more than 13.3 mW, at a wavelength of 1301 nm, for a single-mode photonic-crystal surface-emitting laser under room-temperature is achieved. The increased output power results from a flat band structure of the photonic crystal and an extra feedback mechanism. The surface emission is realized by the diffraction of the photonic crystal and thus no distributed Bragg reflector is needed. Our results promise to overcome present limitations for applications, which suffer from low-power.

Sicong Tian received his B. Sc. and Ph. D. degree in Physics from Jilin University, China. Then he joined CIOMP, CAS in 2012. In 2016-2017 he studied in Arkansas University, US, as a visiting scholar. Currently, he is an Associate Professor at “Bimberg Chinese-German Center for Green Photonics”, CIOMP, CAS. His research interest includes Vertical-cavity surface-emitting lasers, photonic crystal lasers and quantum optics.

Recent efforts to realize classical wave topological materials have given rise to the emerging field of topological photonics. The classical counterpart of the quantum Hall effect are typically achieved by breaking time reversal symmetry, while the nontrivial topologies of the quantum spin Hall effect are usually realized through spin-orbital coupling. Due to the absence of intrinsic Kramers’ degeneracy in classical waves, the classical analogs of the quantum spin Hall effect are realized by constructing pseudo-spins. Apart from polarization (spin), the angular momentum of classical waves also offers an alternative way to control wave propagation. Here in this talk, we show that the non-trivial topology of a system can also be realized using orbital angular momentum through a coupling between the angular momentum and the wave vector. To be more specific, we demonstrate that a system can exhibit angular momentum-dependent topological properties through angular-momentum-orbital coupling. Similar as other topological nontrivial systems, the boundary of such a system possesses one-way edge states that are locked to the angular momentum. Meanwhile, time reversal symmetry is kept in this system. We also provide a proof-of-principle experimental demonstration using a transmission line network. Inside finite systems, we will see that local Chern numbers can be used to characterize the topology of a small cluster of such network systems for each angular momentum subspace. The idea discussed in this work can in principal be generalized to other waves.

Meng XIAO is currently an assistant professor in Wuhan University. Before that, he was a postdoc working with Prof. Shanhui Fan in the electrical engineering department of Stanford University. He got his Ph. D. from the Hong Kong University of Science and Technology (Supervisor: Prof. C. T. Chan) and bachelor’s degree from Wuhan University. Dr. Xiao is now working on topics such as wave functional material, topological photonics and topological phononics.

The unrestricted control of terahertz (THz) waves is important in science and applications, but conventional THz devices suffer from issues of bulky size and low efficiency. Metasurfaces, ultrathin metamaterials that consist of planar subwavelength units (e.g., meta-atoms) with tailored electromagnetic (EM) responses, have demonstrated unprecedented capabilities in controlling EM waves. In this talk, I will summarize our latest efforts in constructing metasurfaces and metadevices for controlling THz waves, both statically and dynamically, generating fascinating physical effects such as high-efficiency photonic spin-Hall effect, background-free Bessel-beam generation, high-efficiency (spoof) surface-plasmon excitation, and dynamically controlled beam steering, etc.

Zhou, Lei received his PhD in Physics from Fudan University, Shanghai, China, in 1997. He then went to Institute for Material Research in Tohoku University (Sendai, Japan) for postdoctoral research. In 2000 - 2004, he was a visiting scholar in Physics Department of the Hong Kong University of Science and Technology. He joined Physics Department of Fudan University in 2004 as a professor, and became a “Xi-De" Chair Professor since 2013. Starting from 1993, Professor Lei Zhou has been working in the fields of magnetism, meta-materials, photonic crystals and plasmonics, and he has published over 160 papers in scientific journals including Nature Materials, Phys. Rev. X, Phys. Rev. Lett., Nano Lett, Light: Science & Applications. He successfully held several international conferences as general chair, co-initiated the A3 metamaterials forums, and was invited to give invited/keynote/plenary talks in many top international conferences. Professor Lei Zhou got many awards, including the NSFC "Grant for Outstanding Young Scientist" (2007), the "Chang Jiang Scholars Program" Chair Professorship (2009), the “OSA Young Scientist Award” (2016) and the “APS Outstanding Referee” (2017). He was elected as an OSA fellow in 2019.