Performance of a compact, continuous-wave terahertz source based on a quantum-cascade laser

We report on the development of a compact, easy-to-use terahertz radiation source, which combines a quantum-cascade laser (QCL) with a compact, low-input-power Stirling cooler. The QCL, which is based on a two-miniband design, has been developed for high output and low electrical pump power. Special care has been taken to achieve a good thermal coupling between the QCL and the cold finger of the cooler. The whole system weighs less than 15 kg including the cooler and power supplies. The maximum output power is 8 mW at 3.1 THz. With an appropriate optical beam shaping, the emission profile of the laser is fundamental Gaussian. The applicability of the system is demonstrated by imaging and molecular-spectroscopy experiments.