Comparison of performance of GaAs-AlGaAs and InGaAs-AlInAsquantum cascade lasers

Abstract
The authors present the lasing characteristics of a dry etched GaAs-AlGaAs quantum cascade laser (λ ≃ 9.5 µm) and compare its temperature performance with that of a similar InGaAs-Almas laser (λ ≃ 8.3 µm). In pulsed operation, the maximum peak power measured for the GaAs-AlGaAs device is 400 mW at 10 K and lasing is observed up to 190 K. The threshold current density (Jth) measured for this sample increases rapidly above 120 K, in contrast to the InGaAs-AlInAs laser, which exhibits a gradual increase of Jth up to 270 K. Temperature-dependent studies of a slightly modified GaAs-AlGaAs laser, in which the confinement of the upper laser level is increased, indicate that this aspect of the design does not limit the high temperature performance.