Magneto-optical nonreciprocity without chirality: Archimedean spirals on InSb

Abstract

We report the observation of magneto-optical nonreciprocity in Faraday geometry in a hybrid metamaterial consisting of an Archimedean spiral metasurface and semiconductor InSb that serves as the magneto-optical medium. None of the metamaterial constituents possesses chirality, which is usually a necessary ingredient for optical nonreciprocity in natural materials when the light travels along the magnetic field direction. We also find that our metamaterial can serve as an optical element for polarization control via magnetic field. Another significant property of our hybrid metamaterial is the emergence of the four different transmittance states, which are observed for the four combinations of the positive and negative magnetic field and the direction of the wavevector of light.