Twin slot antenna coupled graphene THz heterodyne mixer*

The unique hot electron properties of graphene make it an ideal platform for terahertz (THz) heterodyne mixers. However, prior graphene-based heterodyne mixers are designed to operate at cryogenic temperatures and show poor performance above 4 K. In this work, we describe the design of a room temperature graphene based heterodyne mixer optimized to work in the THz spectral range of interest to space based astronomy. The proposed mixer is coupled to a twin slot antenna and a coplanar waveguide transmission line with an impedance matching network. Numerical simulation predicts that the coupling efficiency of the incoming radiation to the graphene mixer is over 90% at 1 THz. The mixer has a predicted intermediate frequency bandwidth of 100 GHz with 90% coupling efficiency. Further, the proposed optimized antenna can match graphene device impedances from 70 Ω – 250 Ω by optimizing the slot width of the antenna. Epitaxial grown quasi- free-standing graphene on silicon carbide substrate was used and it is integrated with a silicon lens. We are currently characterizing the IF mixing bandwidth of our heterodyne mixer at various temperatures and plan to calibrate its sensitivity.