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 /spl mu/W 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.