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

The Mie resonances of high-index nanostructures offer the possibility of manipulating light with extremely low loss. Enhanced optical magnetism, with a concomitant significant increase in the quality factor, can be achieved in high-index metasurfaces by adding a highly reflective backplane to the system. Here, we show that Mie-resonance-based hybrid metasurfaces consisting of an array of amorphous silicon nanodisks on a gold backplane can be used to manipulate light polarization upon reflection. Reflection matrix analysis reveals the nontrivial topological property associated with the Mie resonance of individual nanodisks. The topologically protected polarization conversion effect allows the generation of abundant and diverse polarization in the reflected waves by varying the incident wavevector. By presenting proof-of-concept demonstrations based on nonlinear modeling, we further show that the considered hybrid metasurfaces can serve as a platform for ultrafast all-optical polarization switching of near-infrared light. The topological nature of the metasurfaces’ response offers great flexibility in polarization generation and dynamic modulation.