A Low Noise 2.7 THz Waveguide-Based Superconducting Mixer

We report on a low noise waveguide-based heterodyne mixer utilizing a superconductiang NbN hot electron bolometer (HEB) operating near 2.7 THz. The mixer is an NbN nano-bridge integrated with a gold bowtie planar antenna on an ultra-thin silicon substrate of ~ 2-3 μm thickness. To produce the waveguide embedding circuit for use at such a high frequency, we adopted a novel approach combining UV-lithography and micro-plating techniques. The mixer response agreed precisely with model predictions, and we measured a minimum uncorrected DSB receiver noise temperature of 965 K at an LO frequency of 2.74 THz.