Development of waveguide balanced HEB receivers beyond 2 THz

We are developing balanced waveguide-based receivers operating at THz frequencies for astronomical applications. The receivers are based on NbN HEB mixers and quadrature hybrid coupler. Beyond 1.5 THz, the realization, among others, of waveguides by conventional machining fabrication techniques becomes complicated and innovative techniques such as gold-plating and Silicon micromachining technologies are used. As first step, we already developed a very sensitive single waveguide-based HEB mixer operating around 2.7 THz using the gold-plating technique.