In this paper, we report the results of investigation of 9.5 µm AlGaAs/GaAs and strain compensated 4.7 µm AlInAs/InGaAs/InP QCLs. We also show the results for 9.5 µm lasers based on lattice matched AlInAs/InGaAs/InP structures. The developed GaAs/AlGaAs lasers show the record pulse powers of 6 W at 77 K and up to 50 mW at 300 K. This has been achieved by careful optimization of the MBE growth process and by applying a high reflectivity metallic coating to the back facet of the laser. The 9.5 µm AlInAs/InGaAs/InP lasers utilize AlInAs waveguide and were grown exclusively by MBE without MOCVD regrowth. The short wavelength, strain compensated QCLs were grown by MOCVD. They represent state‐of‐the‐art parameters for the devices of their design. For epitaxial process control, the atomic‐force microscopy (AFM), high resolution X‐ray diffraction (HR‐XRD) and transmission electron microscopy (TEM) were used to characterize the morphological and structural properties of the layers. The basic electro‐optical characterization of the lasers is provided. We also present results of Green's function modeling of mid‐IR QCLs and demonstrate the capability of non‐equilibrium Green's function (NEGF) approach for sophisticated but still computationally effective simulation of laser's characteristics.

The development of charge coupled device thermoreflectance (CCD TR) instrumentation for accurate and rapid evaluation of the thermal characteristics of quantum cascade lasers is demonstrated. The thermal characterization of such devices provides a mode for comparing different operating conditions, geometries and device designs. The method allows for registration of the high-resolution maps of the temperature distribution in a time not exceeding several seconds. The capabilities of the CCD TR are compared with standard TR spectroscopy.

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Switchable, double wavelength generation is demonstrated from a single vertical external cavity surface-emitting laser chip. Power of ~0.5 W for two wavelengths λ≈967 nm and 1,018 nm i.e. within the spectral distance of 51 nm were registered. In the semiconductor heterostructure a single set of nominally identical quantum wells was enclosed in a single, two-mode resonant microcavity. The wavelength switching was induced by the change of the pump power. The increase or decrease of the pump power changes the active region temperature and thus tunes spectrally the gain spectrum to the one of two modes.