Unidirectional reflectionlessness and perfect nonreciprocal absorption in stacked asymmetric metamaterial based on near-field coupling

We propose a scheme for achieving unidirectional reflectionlessness and perfect nonreciprocal absorption at the exceptional point, based on near-field coupling in a stacked asymmetric nanostrip metamaterial structure. The result of theoretical analysis shows good agreement with a numerical simulation. Unidirectional reflectionlessness is realized well in wide ranges of the parameters s and a. The absorbance reaches ∼1 in the +z incident direction, and the contrast ratio of the reflectance between the +z and −z incident directions is ∼1.