Design and fabrication of an antenna-coupled graphene terahertz mixer

Graphene has shown promise for tunable terahertz (THz) technology, including detectors, modulators, filters, and emitters. Graphene exhibits a significant change in conductivity when the Fermi energy is altered by applying a gate voltage. Near the Dirac point, graphene field effect transistors (FETs) show a strongly nonlinear response (i.e. a strong change in resistivity with applied voltage) that can be exploited to provide efficient rectification and mixing of THz signals. Although rectification in graphene field-effect transistors has been demonstrated, heterodyne mixing in the THz band has not been explored.~We examine a THz graphene mixer using an antenna-coupled graphene FET configuration. We will discuss the antenna and graphene device design optimized for heterodyne mixing 0.35 THz.~In addition, fabrication and preliminary measurements of a lower frequency prototype will be presented to demonstrate the principle of the operation.