Fundamental and harmonic mixing at 500 GHz using a superconductor-insulator-normal metal junction

Abstract

We have demonstrated fundamental and harmonic mixing using a PbInAu/InOxPbOx/Ag superconductor-insulator-normal metal tunnel junction mixer designed to operate over the 450–550 GHz frequency range. Direct mixing experiments at up to 1.8 times the gap frequency of the tunnel junction have shown that the mixer works in both fundamental and second harmonic modes, with the highest conversion from the fundamental mode obtained at bias voltages near the gap voltage and the highest conversion from the harmonic mode obtained at zero bias. The measured mixer conversion curves are consistent with our five-port model simulations based on Tucker’s quantum mixer theory [IEEE J. Quantum. Electron. QE-15, 1234 (1979)].