報告題目：Topological photonics: from subwavelength imaging to tunability
報 告 人：Dr. Siying Peng（Stanford University）
Topological photonics use unconventional states of light to carry information for communication and computation. Topological phases of light supported by well-designed and well-fabricated nanostructures have the unique property of suppressing backscattering induced by impurity and bending. Therefore, topological photonic materials hold promise for lossless photon transport in large-scale optical circuitry integration, with potential applications in quantum computing where insensitivity to environmental noises is required. I will introduce our experimental work on two-dimensional hexagonal photonic lattices of silicon Mie resonators with a topological optical band structure in the visible spectral range. We use 30 keV electrons focused to nanoscale spots to map the local optical density of states in topological photonic lattices with deeply subwavelength resolution. By slightly shrinking or expanding the unit cell, we form hexagonal superstructures and observe the opening of a band gap and a splitting of the double-degenerate Dirac cones, which correspond to topologically trivial and nontrivial phases. Optical transmission spectroscopy shows evidence of topological edge states at the domain walls between topological and trivial lattices. I will also discuss our experimental efforts with three-dimensional photonic crystals, where we investigate single gyroid photonic crystals with a mid-infrared bandgap and double gyroid photonic crystals with quadratic bands inside the bandgap. Lastly, I will discuss our recent efforts to understand light induced phase separation process of halide perovskites and the prospect of using the material for dynamically tunable photonic devices.
Siying Peng is a postdoctoral fellow at Stanford University advised by Professor Paul McIntyre in the department of material sciences. She received her PhD from California Institute of Technology advised by Professor Harry Atwater in the physics division. Siying’s research interests include topological photonics, mid-infrared photonics and advanced electron beam characterization methods for nanophotonics. Siying was awarded the GLAM postdoctoral fellowship (2017-2019) and has published in Physical Review Letters, ACS Photonics, etc.