Giant enhancement of Faraday rotation in Weyl semimetal assisted by optical Tamm state

Abstract

Faraday rotation effect possesses a broad range of applications in the design of non-reciprocal optical devices, such as optical isolators and circulators. By introducing conventional magneto-optical materials into resonant micro-structures, the Faraday rotation effect can be greatly enhanced. Nevertheless, the realization of giant Faraday rotation in micro-structure requires a strong external magnetic field. In this letter, we propose a heterojunction structure composed of a one-dimensional photonic crystal and a Weyl semimetal (WSM) layer to realize giant Faraday rotation without requiring an external magnetic field. Assisted by the optical Tamm state supported by the heterojunction structure, the Faraday rotation angle is greatly enhanced to −40.4 degrees and the transmittance still reaches 57.4%. This giant Faraday rotation effect in simple multilayer structure would possess potential applications in the design of compact non-reciprocal optical devices, such as optical isolators and circulators.