Thermally-Electrically Tunable Graphene-Based Guided-Mode Resonant Perfect Absorber

We propose a thermally-electrically tunable perfect absorber based on amorphous silicon (a-Si) and graphene. Numerical results reveal that a perfect absorption with narrow bandwidth can be induced owing to the guided-mode resonance. The thermal tuning of resonant wavelength, realized via the Joule heating, characters a high tuning efficiency and a linear controllability. The linear and thermal tunability is attributed to the linear relationship between refractive index of a-Si and temperature. Moreover, by adjusting the applied gate voltage, the chemical potential of graphene can be electrically modified, leading to a change of optical absorption and enabling a rapid switching of perfect-absorption and perfect-reflection. It is remarkable that the proposed absorber features a simple structure, perfect absorption, and efficient thermal-electric tunability, manifesting tremendous potential applications in modulator, optical switching, selective filter, etc.