Characterization of a quantum cascade laser as local oscillator in a heterodyne receiver at 2.5 THz

A quantum cascade laser operating at 2.5 THz has been investigated with respect to performance parameters which are relevant for a local oscillator in a heterodyne receiver. The beam profile has been measured and transformed in to a close to Gaussian profile resulting in a good matching between the field patterns of the quantum cascade laser and the antenna of a superconducting hot electron bolometric mixer. Noise temperature measurements with the hot electron bolometer and a 2.5 THz quantum cascade laser yielded the same result as with a gas laser as local oscillator.