High-temperature operation of distributed feedback quantum-cascade lasers at 5.3 mu m

High-temperature operation of a low-threshold 5.3 mum quantum-cascade distr ibuted feedback laser is presented. The emission spectrum was single mode w ith more than 20 dB side mode suppression ratio for all investigated temper atures and up to thermal rollover. For 1.5% duty cycle and at 0 degreesC, t he laser emitted 1.15 W of single mode peak power; at 120 degreesC, a value of 92 mW was seen. For a 3 mm long device, we observed a room-temperature threshold current density of 3.6 kA/cm(2). This remarkable performance is m ainly due to a 4 quantum-well active region using a double phonon resonance for the lower laser level. (C) 2001 American Institute of Physics.