Enhanced Faraday rotation by dielectric metasurfaces with Bayesian shape-optimized scatterers.

In this Letter, we demonstrate how to optimize the magneto-optic response of a Huygens metasurface composed of square arrays of all-dielectric nano-disk scatterers. We compare cylindrical and shape-modified disks. Both provide a strongly enhanced Faraday rotation that is accompanied by almost 100% transmittance. The shape modification obtained via a Bayesian optimization algorithm results in a 50% increase in the magneto-optic response compared to the best cylindrical disk, providing 15° of polarization rotation for a 260 nm thick metasurface.