A tunable all dielectric perfect absorber based on hybrid graphene-dielectric metasurface in the mid-infrared regime

Since the metal-based optical absorbers will introduce some disadvantages, such as low melting point, low resistance and thermal conductivity, these factors limit their further application in thermophotovoltaics, modulators, photodetector and other fields. In this paper, a tunable all dielectric perfect absorber based on hybrid graphene-dielectric metasurface is proposed in the mid-infrared regime. According to the results of finite-difference time-domain method, a perfect absorption peak realizes at the wavelength of 9059 nm since the magnetic dipole mode and electric dipole modes excited in the structure meet the condition for degenerate critical coupling, which can be explain by using the coupled mode theory, and the absorption of the structure can be dynamically adjusted by changing the Fermi energy of graphene film. Moreover, the absorption performance of this all dielectric structure manifests polarization insensitivity and keeps good performance under wide angles of incidence. Therefore, we believe our proposed absorber has great application potential in the fields of photovoltaic and thermal detection.