Nonconventional metasurfaces: From non-Hermitian coupling, quantum interactions, to skin cloak

Metasurfaces are optically thin layers of subwavelength resonators that locally tailor the electromagnetic response at the nanoscale. Our metasurface research aims at developing novel designs and applications of metasurfaces that go beyond the classical regimes. In contrast to conventional phase gradient metasurfaces where each meta-atom responds individually, we are interested in developing metasurfaces where neighboring meta-atoms are strongly coupled. By engineering a non-Hermitian coupling between the meta-atoms, new degrees of freedom are introduced and novel functionalities can be achieved. We are also interested in combining classical metasurface with quantum emitters, which may offer opportunities for on-chip quantum technologies. Additionally, we have been designing metasurfaces to realize exciting phenomena and applications, such as ultrathin metasurface cloak and strong photonic spin-Hall effect. In this paper, we review our research efforts in optical metasurfaces in the past few years, which ranges from conventional to novel type of metasurface and from classical to quantum regime.