In this paper, we report a spectral beam combining technique based on discrete quantum cascade lasers at λ ~ 4.8 μm. Good qualities of M2 < 1.3 for both fast and slow axes are obtained. The entire spectrum span is approximately 29.1 cm−1, which consistent with the theoretical results grating equation. Maximum efficiency 58.9% output power exceeding 1 W demonstrated under continuous wave operati...

Detailed simulations for Terahertz quantum cascade lasers based on two-well designs are presented. We reproduce the maximal operation temperatures observed and attribute degradation with temperature to occupation of parasitic levels thermal backfilling. Furthermore, we demonstrate that current injection can be conveniently studied by using EZ states, which combine energy selectivity spatial loc...

A novel all-electrical method of frequency noise reduction in quantum cascade lasers (QCLs) is proposed. Electrical current through the laser was continuously adjusted to compensate for fluctuations of the laser internal resistance, which led to an active stabilization of the optical emission frequency. A reduction of the linewidth from 1.7 MHz in the standard constant current mode of operation...