Quantum Cascade Lasers for semiconductor heterodyne receiver

Recently proposed detectors based on disordered semiconductor heterostructures are well coupled to THz radiation and require substantially less power of the local oscillator (LO) than the widely used Schottky diodes. Integration of these detectors with Quantum Cascade Lasers (QCLs) for THz heterodyne sensing is very promising for numerous applications of THz spectroscopy. In this work, we have fabricated and characterized THz QCLs grown on GaAs/AlGaAs superlattice based on LO-phonon depopulation mechanism. The designed QCLs operate with a stable continuous-wave single-mode operation in the range of 2-3 THz and the effective line-width is in MHz scale. The peak power in the designed QCLs is estimated to be ~30 μW at 77K and ~ 0.3 mW at 4K. Manageable spectral characteristics have been achieved using selective devices and by varying the applied bias.