Magneto-Optical Metasurfaces Based on Bismuth Iron Garnet

We numerically investigate magneto-optical metasurfaces composed of Bismuth Iron Garnet (BIG), focusing on their dynamically tunable optical properties under external magnetic fields. Using finite-difference time-domain (FDTD) simulations, we systematically explore the influence of magnetization on the optical resonance characteristics and phase modulation capabilities of metasurface unit cells. The results demonstrate pronounced non-reciprocal optical behavior, showing significant resonance shifts and enhanced wavefront modulation achievable through external magnetic control. Leveraging these magnetically tunable properties, we propose the designed BIG metasurface as a viable platform for actively tunable metalenses, presenting a comprehensive lookup table relating structural parameters to desired optical responses. This work provides essential guidelines toward designing adaptive, high-performance photonic metasurfaces and paves the way for future metalens implementations.