Optical isolator based on a subwavelength integrated optical metawaveguide

Dielectric metawaveguides that leverage the resonant behavior of individual dielectric scatterers have recently been suggested as a versatile platform for controlling light propagation and tailoring light–matter interactions in integrated optical circuits. Their broad tunability is of particular interest for the realization of various reconfigurable optical elements. Here, we propose an approach for realizing optical isolation based on a metawaveguide composed of silicon nanoparticles exhibiting a predominant in-plane electric dipole response. We show that perturbation of the metawaveguide geometry leads to the formation of modes with a non-zero transverse optical spin through the mode coupling mechanism. Furthermore, by incorporating magnetic material into the waveguide, we demonstrate a compact optical isolator compatible with the silicon-on-insulator platform and provide a general framework for its design. Our results have significant implications for the advancement of high-density photonic circuits and may enable functionalities in directional emission, optical communications, and sensing technologies.