Abstract
Metasurfaces, ultra-thin structured surfaces with subwavelength unit cells, have emerged as a versatile and compact platform to develop advanced photonic devices. Optical metasurfaces have received broad interest due to their unique ability to modulate the light wavefronts. They can provide distinct complex amplitude modulation of light scattering in the nanometer scale, which is in dramatic contrast to the conventional elements such as lens, polarizers, waveplates etc. Previous studies have focused on functionalities of metasurfaces for manipulating free-space light, while on-chip integration of such meta-devices with active materials has been much less investigated. As part of this project, I will explore the interaction of optical metasurfaces with 2D materials such as transition metal dichalcogenide (TMDs). Metasurfaces will not only allow a strong interaction with the transition of the 2D systems, but also provide a viable way to manipulate the emission of light from the 2D materials. In addition, it is possible to realize the photonic spin Hall effect in a metasurface exhibiting hyperbolic dispersion.
On the other hand, when the wavelength is comparable to or smaller than the unit cells of nanostructures, these systems cannot be treated as an effective medium. In this case, interesting photonic band structures can be engineered to exhibit nontrivial topological properties. Recently, the local density of states (LDOS) of photonic crystals has been proposed as a probe to reveal the distinct topological phases. Previous detections of non-trivial topological phases rely on revealing topological boundary states such as topological edge/corner states. In this project, based on the change of LDOS and the number of modes, we will look into the manifestation of topological phase transitions by the signatures of the bulk modes.
Anyone interested is welcome to attend.