  Weyl semimetals hold great promise in revolutionizing nonreciprocal optical
components due to their unique topological properties. By exhibiting
nonreciprocal magneto-optical effects without necessitating an external
magnetic field, these materials offer remarkable miniaturization opportunities
and reduced energy consumption. However, their intrinsic topological robustness
poses a challenge for applications demanding tunability. In this work, we
introduce an innovative approach to enhance the tunability of their response,
utilizing multilayered configurations of twisted anisotropic Weyl semimetals.
Our design enables controlled and reversible isolation by adjusting the twist
angle between the anisotropic layers. When implemented in the Faraday geometry
within the mid-IR frequency range, our design delivers impressive isolation,
exceeding 50 dB, while maintaining a minimal insertion loss of just 0.33 dB.
Moreover, the in-plane anisotropy of Weyl semimetals eliminates one or both
polarizers of a conventional isolator geometry, significantly reducing the
overall dimensions. These results set the stage for creating highly adaptable,
ultra-compact optical isolators that can propel the fields of integrated
photonics and quantum technology applications to new heights.
