Electrically Tunable Metasurface Reflector based on Graphene-Metal Plasmon Interactions on a Silver Grating

We propose a tunable metasurface reflector that integrates a passive metasurface with graphene-a two-dimensional material-to enhance reflectance modulation efficiency under an external voltage. The device comprised a silver substrate with etched air grooves, an aluminium oxide spacer layer, and a single graphene layer. The metasurface was designed to intensify light-matter interactions, increasing the modulation efficiency of graphene. Two passive metamaterials, differing in meta-atom size, were investigated. Smaller meta-atoms produced a narrower reflective notch, whereas larger meta-atoms enhanced the modulation efficiency of graphene. The rectangular periodic silver plates and graphene layer were optimized for operation at a 1550 nm wavelength. The reflectance of the open-hole mirror, composed of graphene and the spacer, can be electrically modulated by biasing the graphene. The optical conductivity of graphene was modeled using the local random phase approximation, with its Fermi level directly proportional to the applied voltage bias. This tunable metasurface reflector provides a straightforward and effective method for controlling light-matter interactions, with potential applications in optical devices, such as filters, sensors, and modulators.