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Room temperature, single mode, pulsed emission from two-section coupled cavity InGaAs/AlGaAs/GaAs quantum cascade laser fabricated by focused ion beam processing is demonstrated and analyzed. The single mode emission is centered at 1059.4 cm–1 (9.44 µm). A side mode suppression ratio of 43 dB was achieved. The laser exhibits a peak output power of 15 mW per facet at room temperature. The stable, single mode emission is observed within temperature tuning range, exhibiting shift at rate of 0.59 nm/K. [ABSTRACT FROM AUTHOR]

We investigate growth conditions for strain-compensated In0.67Ga0.33As/In0.36Al0.64As/InP quantum cascade lasers (QCLs) by solid-source molecular beam epitaxy (SSMBE). The extensive discussion of growth procedures is presented. The technology was first elaborated for In0.53Ga0.47As/In0.52Al0.48As material system lattice matched to InP. After that QCLs with lattice matched active region were grown for validation of design and obtained material quality. The next step was elaboration of growth process and especially growth preparation procedures for strain compensated active regions. The grown structures were examined by HRXRD, AFM, and TEM techniques. The on-line implementation of obtained results in subsequent growth runs was crucial for achieving room temperature operating 4.4-μm lasers. For uncoated devices with Fabry-Perrot resonator up to 250 mW of optical power per facet at 300 K was obtained under pulsed conditions. The paper focuses on MBE technology and presents developed algorithm for strain-compensated QCL growth. [ABSTRACT FROM AUTHOR]

In this paper, the X-ray diffraction profiles of Quantum Cascade Laser (QCL) structures have been investigated. The examined structures were grown by molecular beam epitaxy. The crystallographic characterization was carried out using high resolution X-ray diffractometer. The information about thickness of individual layers and periodicity of the structures was derived from simulation of diffraction profiles calculated using dynamical diffraction theory. The influence of interface roughness on the shape of satellite peaks was studied. The particular attention has been paid to the analysis of the broadening of satellite peaks. The presented results show that broadening is due to the variation of thickness of individual layers. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]