A plasmonic waveguide end-coupled to two plasmonic cavities in a non-Hermitian quantum system for dual-band unidirectional reflectionlessness

Abstract

Abstract We demonstrate the possibility of dual-band unidirectional reflectionlessness in a non-Hermitian quantum system composed of a plasmonic waveguide and two end-coupled plasmonic cavities (PCs). Our scheme exhibits dual-band unidirectional reflectionlessness can be obtained at exceptional points by properly adjusting the coupling strength between two PCs, the ratio of decay rates of two PCs, and the ratio of plasmonic cavity-waveguide coupling strengths. As a valuable feature, the quality factor reaches to ∼175.4 in forward direction, while the backward quality factor is close to ∼188.2.