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

Abstract

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.

Circular Displacement Current Induced Anomalous Magneto‐Optical Effects in High Index Mie Resonators

“…The strong optical confinement in this resonant structure may also allow excitation of spin wave resonances in the magnetic system for opto‐spintronic device applications. [ 23,52 ] These possibilities make high index contrast, all‐dielectric magneto‐optical metasurfaces promising for a variety of applications including vectoral magnetic field sensing, free space non‐reciprocal photonic devices, magneto‐optical imaging and optomagnetic memories.…”

Topological scattering singularities and embedded eigenstates for polarization control and sensing applications

“…Thus, a topological charge cannot be defined by integrating in k-space like in PCs, but in real space (either in ω-d or ω-θ space). Somewhat analogous to breaking spatial symmetries in PCs, which splits the EE into two half-integer charges [30], dissipation in our system lifts the degeneracy of two singularities of opposite integer charge, destroying the EE. Since all real systems have losses, this degeneracy is always lifted, whereas EEs in PCs remain topologically protected as long as spatial symmetries are not broken.…”

“…The topological nature of EEs has spun-off several research efforts, exploring the merging of EE charges to produce even more confined resonances in realistic systems [26] and unidirectional guided modes within the continuum [27]. The topological properties of EEs have been especially useful for polarization control, as it was shown that topologically protected polarization conversion is possible [28][29][30], and circularly polarized states can arise from BICs by breaking spatial symmetries [31][32][33]. Recently, the generation of vortex beams through EEs [34] and efficient topological vortex laser generation [35] were demonstrated, showing the potential of topological phenomena in radiative and scattering processes.…”

Low-Symmetry Nanophotonics

“…It was also shown that the merging of BIC charges enables even more confined resonances in realistic systems 172 and unidirectional guided modes within the continuum 173 . The topological properties of the BIC have been particularly useful for polarization control, as it has been shown to be possible to convert polarization with topological protection [174][175][176] , and circularly polarized states can arise from BICs by breaking spatial symmetries [177][178][179] . The generation of vortex beams at BICs 180 and efficient generation of topological vortex 181 have been recently demonstrated.…”