Terahertz heterodyne receiver with quantum cascade laser and hot electron bolometer mixer in a pulse tube cooler

A liquid cryogen-free terahertz heterodyne receiver in a pulse tube cooler has been realized. The receiver operates at 2.5 THz. It is based on a quantum cascade laser (QCL) as local oscillator and a hot electron bolometric mixer. A detailed study of the QCL beam quality yielded a beam propagation factor of 1.1–1.2. The double sideband noise temperature of the system is 2000 K and when corrected for optical losses in the signal path it is ∼800 K.