Continuous wave operation of a 9.3 mu m quantum cascade laser on a Peltiercooler

High average power quantum cascade lasers at 9.3 mum using InP top cladding layers and both junction up and junction down mounting are presented. A 3 mm long, junction up mounted device emitted 54 mW average power at 30 degre esC and 11.5% duty cycle with a threshold current density of 3.72 kA/cm(2). A similar, but only 1.5 mm long device with high reflection coating on bot h facets was mounted junction down and tested at even higher duty cycles. A t -27 degreesC, we achieved continuous wave operation with a threshold curr ent density of 3.3 kA/cm(2). (C) 2001 American Institute of Physics.