Geometric Phase and Nonlinear Photonic Metasurfaces
By designing an ultrathin metasurface, which consists of spatially variant plasmonic structures with engineered geometric Berry phase, it is shown that spin-orbit coupling of light can be utilized to manipulate both the spin and orbital angular momentum of light. It was demonstrated that the spin dependent metasurface can be applied to design highly efficient optical holograms, which have important applications in the areas including holographic displays, beam shaping, data storage, optical trapping, optical tweezers and so on.
In nonlinear optical regime, we applied the concept of nonlinear geometrical Berry phase for designing nonlinear photonic metasurfaces. For example, in a second- and third- harmonic generation processes, the plasmonic meta-atoms, with certain rotational symmetries, can acquire a nonlinear geometric Berry phase of 3θ, 4θ, where θ is the in-plane orientation angle of the meta-atoms. This nonlinear phase can be continuously tuned by from zero to 2π by simply varying theta. Several interesting applications such as nonlinear image encryption, nonlinear spin-orbit interaction and so on will be discussed.
Renmin Ma, Peking University, China+
Eigenmode Engineering of Nanolasers
Nanolasers generate coherent light at the nanoscale. In the past decade, they have attracted intense interest, because they are more compact, faster and more power-efficient than conventional lasers. The eigenmode of a nanolaser can be engineered in a controllable manner for novel inner laser cavity field and/or emission beam synthesis. Furthermore, ensembles of nanolasers operating in unison can provide a macroscopic response that would not be possible in conventional lasers.
Guohai Situ, Shanghai Institute of Optics and Fine Mechanics, China+
Data-Driven Computational Optical Imaging
It is well known that neural networks including deep learning have been widely employed to solve the problems in recognition and classification. It was not until recently that people started to use them to solve imaging problems. In this lecture, I will first introduce the basic concept of deep learning, and then discuss how it can be adopted to solve computational imaging problems. In particular, I will talk about three use cases: computational ghost imaging, imaging through scattering media, and digital holography.
Yun-feng Xiao, Peking University, China +
Ultra-high-Q microcavity optics and photonics
Confinement and manipulation of photons using microcavities have triggered intense research interest in both fundamental and applied photonics for more than two decades. Prominent examples are ultrahigh-Q whispering gallery microcavities which confine photons by means of continuous total internal reflection along a curved and smooth surface. The long photon lifetime, strong field confinement, and in-plane emission characteristics make them promising candidates for enhancing light-matter interactions on a chip. In the first part of this talk, I will introduce some representative photonics applications of ultrahigh-Q microcavities. In the second part, I will focus on (1) chaos-assisted momentum transformation in an asymmetrical microcavity, (2) spontaneous symmetry breaking of optical fields in a single ultrahigh-Q microcavity, and (3) second-order nonlinear optics induced by symmetry breaking at the surface of a silica microcavity under a sub-milliwatt continuous-wave pump.
Qihua Xiong, Nanyang Technological University, Singapore+
PerovLight: Perovskite Materials for Emergent Nanophotonics and Polaritonics
Halide perovskites have recently attracted tremendous attention due to their remarkable properties as an optical gain material, which have shown high performance in solar cells, light-emitting diodes, photodetectors and many other optoelectronic applications. In this talk, I will first review our recent progress in the investigation of halide perovskite materials as excellent optical gain materials, which can be synthesized by either physical or chemical ways. Steady-state and transient spectroscopy approaches can elaborate the large exciton binding energy higher than room temperature thermal excitation energy, and exciton dynamics. High crystalline quality supports the optically pumped photonic lasing based on the intrinsic whispering gallery mode cavity, while the lasing quality factor can be as high as 5000 in all-inorganic perovskite crystals. Next, I will present our experimental realization of room-temperature polariton lasing in all-inorganic cesium lead chloride perovskite crystals embedded in two distributed Bragg reflectors. The perovskite crystals possess efficient polariton-polariton scattering due to the Wannier-Mott exciton nature with large binding energy. The polariton lasing is evidenced by a superlinear power dependence, macroscopic ground state occupation, and increase of the temporal coherence. Finally, we will present our recent results using perovskite materials towards highly efficient light-emitting diode (LED) applications, with a recent record high >20% conversion efficiency in green emission region. This progress also suggests the possibility towards electrically pumped lasing devices.
Jia Zhu, Nanjing University, China +
Nanophotonic designs for energy conversion and storage
Transformation of traditional energy system to a sustainable one requires developments of chemical and physical processes that can take advantage of renewable energy sources.
Nanophotonics, with the ultimate spatial and temporal control over light, offers tremendous opportunities, to manipulate, enhance and/or monitor these physical or chemical processes. In this talk, I will summarize some of recent progress on this front.
Arseniy Kuznetsov/Shiqiang Li, Institute of Materials Research and Engineering, ASTAR, Singapore+
Toward active dielectric metasurface devices
High refractive-index nano-antennas capture the best of both worlds – the strong interaction with light comparable to that of plasmonics and the low absorption loss of dielectrics. In the past few years, increasing interest has been seen toward discovering new properties and new applications of these nano-antennas, enabled by the advancement of nano-fabrication techniques. Many useful devices, static or dynamic, have been demonstrated. In this talk, I will start with a review of the development of technologies based on dielectric nano-antennas in our group. Then, I will elaborate on our recent push on large scale metalens fabrications and the latest development of spatial light modulators based on tunable dielectric metasurfaces.
