High performance short wavelength InP-based quantum cascade lasers

Abstract

We review the development of high performance, short wavelength (3 μm < λ < 3.8 μm) quantum cascade lasers (QCLs) based on the deep quantum well InGaAs/AlAsSb/InP materials system. Use of this system has enabled us to demonstrate room temperature operation at λ ~ 3.1 μm, the shortest room temperature lasing wavelength yet observed for InP-based QCLs. We demonstrate that significant performance improvements can be made by using strain compensated material with selective incorporation of AlAs barriers in the QCL active region. This approach provides reduction in threshold current density and increases the maximum optical power. In such devices, room-temperature peak output powers of up to 20 W can be achieved at λ ~ 3.6 μm, with high peak powers of around 4 W still achievable as wavelength decreases to 3.3 μm.