THz quantum cascade lasers with large wall-plug efficiency

Improved optical power performance of bound-to-continuum quantum-cascade lasers operating at 2.83 THz is reported. Peak optical powers of 100 mW at 4 K and power conversion-efficiencies as high as w=5.5±0.4% in continuous wave at 40 K were measured. The w values were assessed via an experimental method based on the analysis of the local lattice temperature as extracted by microprobe photoluminescence versus electrical power. From the measured w values they extracted a slope efficiency value 0.41±0.11 W/A