Dynamically tunable multi-band coherent perfect absorption based on InSb metasurfaces

Abstract

We propose a composite metasurface composed of InSb strips and SiO2 substrate, which can achieve multi-band coherent perfect absorption in the terahertz frequency range. It is demonstrated that InSb strips of different sizes support independent plasmon resonances at different frequencies, which is a linear superposition of each subunit. The absorption at each resonance frequency can be independently and continuously modulated with the modulation depth is up to 1.332 × 104 via controlling the relative phase or relative intensity of two beams. Meanwhile, the absorber has the sensitivity of the refractive index to the surrounding environment, thereby facilitating the design of sensing devices. Moreover, it has excellent thermal tunability: we flexibly modulate absorption via controlling the temperature without restructuring. Our design contributes a feasible way of manipulating the interaction between light and matter, which can be applied to the field of micro–nano photonic devices in the terahertz band.