Polarization-insensitive graphene photodetectors enhanced by a broadband metamaterial absorber

Graphene, combined with plasmonic nanostructures, shows great promise for achieving desirable photodetection properties and functionalities. Here, we theoretically proposed and experimentally demonstrated a graphene photodetector based on the metamaterial absorber in the visible and near-infrared wavebands. The experimental results show that the metamaterial-based graphene photodetector (MGPD) has achieved up to 3751% of photocurrent enhancement relative to an antennasless graphene device at zero external bias. Furthermore, the polarization-independent of photoresponse has resulted from the polarization-insensitive absorption of symmetric square-ring antennas. Moreover, the spectral-dependent photocurrent enhancement, originated from the enhanced light-trapping effect, was experimentally confirmed and understood by the simulated electric field profiles. The design contributes to the development of high-performance graphene photodetectors and optoelectronic devices.