Experimental demonstration of deflection angle tuning in unidirectional fishnet metamaterials at millimeter-waves

Asymmetric transmission enables high forward-to-backward transmission contrast in the Lorentz reciprocal framework, so that it is envisioned to be a backbone of future practical devices with strong directional selectivity. In this letter, we experimentally demonstrate efficient tuning and sign-switching capabilities of the deflection angle by varying the incidence angle and/or frequency in the unidirectional regime of a compact and simple structure comprising a stack of a fishnet metamaterial and a dielectric grating. The entire device operates at frequencies ranging from 45 to 75 GHz and has a total thickness of 0.77λ₀ at 60GHz.