Short Wavelength InGaAs-AlAsSb-InP Quantum Cascade Lasers

As longer wavelength mid-infrared quantum cascade lasers (QCLs) approach some degree of technological maturity, attention is increasingly turning to the development of high performance devices in the 3-4 mum range, where numerous technological applications exist. A fundamental problem arises, however, with the established InGaAs-AlInAs QCL materials system at these wavelengths, due to the limited quantum well depth (DeltaE_c) available to support high energy intersubband transitions. Although some success has been achieved with highly strain compensated InGaAs-AlInAs-InP (DeltaE_c~700meV), it seems likely that the most promising route to high performance sources, particularly at wavelengths less than ~3.5 mum, is to investigate the development of QCLs in new materials systems with high DeltaE_c.