Polarization-dependent thermal-tunable graphene-based metamaterial exploiting critical coupling with guided mode resonances

Abstract

A polarization-dependent thermal-tunable graphene metamaterial consisting of a graphene monolayer, amorphous silicon photonic crystal, and lossless metallic mirror is proposed to realize manipulation of light absorption. Benefiting from the 90° rotational asymmetry of the structure, anisotropic absorption can be obtained. We attribute the perfect absorption to the critical coupling with guided resonance, which can be well analyzed by the coupled mode theory. By adjusting the polarization angle, the absorption amplitude can be flexibly controlled, so that a variety of related functions can be realized, including single- or dual-channel absorbers, modulators, and switches, as well as spectral engineering. Intriguingly, the spectral response can be accurately controlled by thermal tuning with a tuning efficiency of 0.12 nm/°C, and such tuning does not affect the spectral characteristics. The thermo-optic tunable graphene-based metamaterial is particularly desirable for various potential applications.