We propose a scheme to achieve a controllable unidirectional reflectionless propagation at exceptional point (EP) in a non-ideal parity-time metasurface consisting of two silver ring resonators. The unidirectional reflectionless propagation can be manipulated by simply adjusting the angle of incident wave and the distance s between two silver rings based on the far field coupling. In addition, the angle of incident wave in a wide range of ∼25° is available to achieve the unidirectional reflectionless propagation. Moreover, the unidirectional reflectionless propagation at EP is insensitive to the polarization of incident wave due to the two-ring structure.

Dual-band unidirectional reflectionlessness and coherent perfect absorption (CPA) are demonstrated in a non-Hermitian plasmonic waveguide system based on near-field coupling between a single resonator and the resonant modes of two resonators showing an electromagnetically induced-transparency-like (EIT-like) effect. The non-Hermitian plasmonic system consists of three metal-insulator-metal (MIM) resonators coupled to a MIM plasmonic waveguide.

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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.

We propose a scheme for realizing plasmonic electromagnetically induced transparency (EIT)-like effects at optical frequencies in a stacked metamaterial that consists of two silver rings. The two silver rings are excited strongly by an incident wave. Based on Fabry–Pérot (FP) resonance coupling between the two resonators, polarization-independent EIT-like effects appear at optical frequencies.