Space-Time Modulated Loaded-Wire Metagratings for Magnetless Nonreciprocity

We show that spatiotemporally modulated metagratings can lead to strong nonreciprocal responses, despite the fact that they are based on electrically-large unit cells and use only three modulation domains. We specifically focus on wire metagratings loaded with time-modulated capacitances. We use the discrete-dipole-approximation and an ad-hoc generalization of the theory of polarizability for time-modulated particles, and demonstrate an effective nonreciprocal anomalous reflection (diffraction) with an efficient frequency conversion.