Graphene-based optical photodetector exploiting hybrid plasmonic waveguide to enhance photo-thermoelectric current

Abstract

A graphene-based optical photodetector with a symmetric hybrid plasmonic waveguide that integrates two high-refractive-index dielectric slabs as a finite-width insulator-metal-insulator (IMI) structure is proposed and investigated at . It is shown that by electrically tuning the graphene refractive index, the gap between the silicon slabs and graphene strip as a hybrid plasmonic waveguide results in modified modal behavior over the graphene layer. This highly lossy hybrid surface plasmon polariton strip mode enhances optical absorption in the graphene channel. An analytical approach reveals that this highly confined absorption creates a highly asymmetric hot-carrier spatial temperature profile along the channel. Based on photo-thermoelectric (PTE) effect, this asymmetric temperature profile along with applied source-drain voltage (Vds) creates a PTE current. Coupled to the super plasmonic mode of hybrid plasmonic waveguide (HPW) mechanism, this photodetector exhibits a maximum responsivity of . In addition, for the proposed HPW graphene photodetector (HPW-GPD), the calculated effective mode area, the propagation length and modal propagation loss are , and , respectively.