Optically driven effective Faraday effect in instantaneous nonlinear media

Abstract

Faraday rotation is arguably the most widely studied nonreciprocal phenomenon, observable in the form of polarization rotation as waves travel in magneto-optical materials. It is at the basis of the realization of various forms of isolators and circulators. However, magneto-optical materials are bulky and difficult to integrate, and inherently associated with losses. Here we leverage nonlinear phenomena in conventional optical crystals to mimic Faraday rotation in a resonant cavity excited with two pumps with opposite circular polarizations and slightly detuned frequencies. The effect can be observed in basic resonant structures with no need for material resonances or tailored dispersion, arbitrary frequency of the pumps, and low loss, yielding an interesting path towards the realization of compact magnet-free nonreciprocal optical elements.