Intersubband Emitters: GaAs-based Quantum-Cascade Lasers

Quantum-cascade lasers based on the GaAs/(Al,Ga)As materials system are already very useful radiation sources for many applications in the terahertz (THz) spectral region. This spectral region ranges typically from 0.1 to 10 THz bridging the electronics-based microwave region with the optics-based infrared region.

Due to their high emission powers and narrow line widths in continuous-wave operation, THz quantum-cascade lasers are excellent emitters of electromagnetic radiation for high-resolution spectroscopy. The THz region is of great current interest for spectroscopic applications, since rotational states of many molecules, impurity transitions in semiconductors, and fine-structure transitions in atoms as well as ions can result in THz absorption or emission. Currently, quantum-cascade lasers are unrivaled for local oscillators at frequencies above 3 THz in heterodyne detectors. Furthermore, imaging with THz radiation can be used for material testing or security purposes. The key challenges are the increase of the practical operating temperature and the wall plug efficiency of THz quantum-cascade lasers. The practical operating temperature is determined by an output power of at least 1 mW in continuous-wave operation.

Dr. Lutz Schrottke
+49 30 20377-339