Compact heterodyne receiver at 2.8 THz based on a quantum cascade laser and a superconducting bolometer

We report here a sensitivity measurement of an all solid-state heterodyne receiver which uses a twin slot antenna coupled, small superconducting NbN hot electron bolometer as mixer and a semiconductor quantum cascade laser operating at 2.8 THz as local oscillator. We measure a double sideband receiver noise temperature of 3200 K at 2.8 THz and 4.2 K. We find that the optimal LO power is 33 nW measured at HEB and 1.3 μW estimated at the QCL, much lower than the output power of the QCL. Such a receiver can be used for high-resolution spectroscopy above 2 THz and is particularly suitable for space-based observatories.