Terahertz quantum cascade lasers with large wall-plug efficiency

Improved optical power performance of bound-to-continuum quantum-cascade lasers operating at 2.83THz is reported. Peak optical powers of 100mW at 4K and power conversion-efficiencies as high as ηw=(5.5±0.4)% in continuous wave at 40K were measured. The ηw 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 ηw values they extracted a slope efficiency value 0.41±0.11W∕A.