Nonreciprocal absorber of subwavelength metallic gratings

A dual-band non-reciprocal absorber, which is composed of the silver grating with a thin SiO2 layer, is proposed in near-infrared region. When the transverse magnetic wave illuminates on the thin metallic gratings, two SPPs modes (anti-symmetrical and symmetrical modes) can be excited, making the two absorption bands come into being. When a thin SiO2 layer is added on one side of the metallic gratings, one of the two SPPs modes can be enhanced and the other is inhibited. By carefully choosing the thickness of the SiO2 layer, the dual-band nonreciprocal absorber can be achieved. (C) 2018 The Japan Society of Applied Physics.