Active magneto-optical metalens

We demonstrate a metasurface made of bismuth-substituted yttrium iron garnet (BIG) nanodisks that, in the presence of a magnetic field, functions as a polarization-sensitive metalens. Specifically, switching the handedness of the incident circularly polarized light (from right- to left-handed or vice versa) results in distinct focusing behavior. We provide a full-wave simulation study of the metalens performance, considering the response of the BIG nanodisks, the resultant phase profile in comparison with the target one, and the platform focusing efficiency. Our findings establish a foundational framework for developing active metadevices whose optical response can be modulated by an external magnetic field.