Cavity-Enhanced Giant Magneto-Optical Linear Dichroism in van der Waals CrSBr.

Compact magneto-optical dichroism devices facilitate active and dynamic manipulation of photons at the chip scale, making them a key focus in the development of integrated photonic and optoelectronic systems. However, the performance of existing optical anisotropy materials is often constrained by their narrow operational bandwidth and temperature and insufficient magnetically induced tunability. Herein, we demonstrate robust and reconfigurable magneto-optical dichroism spanning the visible to near-infrared spectrum using a quasi-1D exciton-polariton cavity platform constructed from van der Waals CrSBr crystals. The platform demonstrates strong and multiparameter-tunable in-plane linear dichroism, responsive to magnetic field, temperature, and crystal thickness variations. The anisotropy in exciton-photon coupling is the origin of the superior and tunable in-plane anisotropy, which is enhanced by the optical cavity. We further demonstrate the effective modulation of the left- and right-circularly polarized components in anisotropy-induced optical spin-orbit coupling in CrSBr microcavities. These results offer valuable insights for the development of compact isolators, modulators, and polarizers for photonic, quantum, and optoelectronic applications.