Independently tunable dual-band cross-shaped metal-insulator-metal infrared perfect absorber

Abstract

The dual-band cross structured metal–insulator–metal infrared perfect absorber (CS-MIM-IPA) has promising applications in refractive index sensing, solar cells, thermal infrared (IR) sensor, and IR microscopy. In this study, we have demonstrated an independent modulation of the dual-absorption bands (corresponding to SPP and LSP excitation) of the CS-MIM-IPA structure. The results show that the peak position of the LSP mode and SPP mode can be independently controlled by the arm length and the period size, respectively and the underlying mechanism is presented. Furthermore, the role of plasmon coupling effects and space ratio of the cross-structure in balancing the absorption intensity of the LSP modes had been revealed.