Independently tunable perfect absorber based on the plasmonic properties in double-layer graphene

Graphene can be utilized in designing tunable photonic devices due to its unique properties such as high optical transparency and tunable conductivity. In this paper, a tunable triple-band perfect absorber is designed and numerically demonstrated, which is composed of a stacked graphene nanodisk, L-shape graphene layer and a gold ground plane spaced by insulator layers. The results show that there are three higher than 99% absorption peaks in the infrared range with a wide incident angle range up to 50 degrees, and the absorber is insensitive for TE and TM polarized incident light. Moreover, the perfect absorption peak wavelength can be tuned by changing Fermi levels or geometric parameters of graphene layers. The findings above indicate that the designed perfect absorber can be used in the field of photodetectors, thermal emitters and photovoltaics. (C) 2019 Elsevier Ltd. All rights reserved.