Exploiting Topological Properties of Mie-Resonance-Based Hybrid Metasurfaces for Ultrafast Switching of Light Polarization

Mie resonances of high-index dielectric matesurfaces provide large freedom for light modulation with low loss, which, by including a highly reflective backplane, induce an enhanced optical magnetism with increasing quality factor. In this paper, we show that Mie-resonance-based α-Si:H metasurfaces with a gold backplane can be utilized to manipulate light polarization upon reflection. The nontrivial topological properties associated with the scattering field are revealed by reflection matrix analysis. Topologically protected polarization conversion is demonstrated by varying the incident wavevector. Furthermore, the nonlinear modeling shows that such hybrid metasurfaces can realize ultrafast all-optical polarization switching of near-infrared light. The topological nature of the metasurface's response offers great flexibility in polarization generation and dynamic modulation.