Ultra-low Threshold Quantum Cascade Laser

Quantum cascade lasers (QCLs) are widely used in the mid-infrared region for spectroscopic and gas-sensing applications. Due to the high operating voltage and typically Watt-level input power, bulky cooling systems are generally needed for driving a QCL at continuous-wave operation, which limit QCL applications on portable platforms. One approach for reducing the threshold dissipation power of a QCL is the combination of small volume devices, with state-of-the-art active regions and high reflectivity facets. Previously, the threshold current of 22 mA was presented [1] .