High performance GaAs based quantum cascade lasers

Summary form only given.At present, only two material systems have been successfully exploited to demonstrate quantum cascade (QC) lasers: GaInAs-AlInAs grown on InP and more recently GaAs-AlGaAs. Although there are no significant conceptual differences in the quantum design between these two classes of lasers, the use of different materials has important consequences on device characteristics and has to be included in device optimisation. We report on AlGaAs QC lasers optimised for output power and maximum operating temperature in the 9-12 /spl mu/m wavelength range. In these structures the waveguide is Al-free and we use AlGaAs layers only in the active region, to define the tunnelling barriers. The claddings are obtained by sandwiching the active region between two thick GaAs layers, with an appropriate doping profile.