Nonthermal carrier distributions in the subbands of 2-phonon resonance mid-infrared quantum cascade laser

Kolek, Andrzej; Hałdaś, G.; Bugajski, M.

doi:10.1063/1.4745013

Cited by 34 publications

(24 citation statements)

References 16 publications

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“…Figure 5 shows the in-plane energy distribution for different subbands at a field strength of 82 kV/cm, for lattice temperatures of 160 K (left panel) and 298 K (right panel). Nonthermal electron distributions have been obtained previously using both semiclassical and quantum transport approaches for various QCL structures in the mid-IR [25,33,46,47]. The in-plane distributions for the injector and upper lasing levels have similar shapes: at low energies (0-100 meV), both distributions are well described by a heated Maxwellian (i.e., they are linear in these semilog plots).…”

Section: Resultsmentioning

confidence: 90%

Quantum Transport Simulation of High-Power 4.6-μm Quantum Cascade Lasers

et al. 2016

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We present a quantum transport simulation of a 4.6-µm quantum cascade laser (QCL) operating at high power near room temperature. The simulation is based on a rigorous density-matrix-based formalism, in which the evolution of the single-electron density matrix follows a Markovian master equation in the presence of applied electric field and relevant scattering mechanisms. We show that it is important to allow for both position-dependent effective mass and for effective lowering of very thin barriers in order to obtain the band structure and the current-field characteristics comparable to experiment. Our calculations agree well with experiments over a wide range of temperatures. We predict a room-temperature threshold field of 62.5 kV/cm and a characteristic temperature for threshold-current-density variation of T 0 = 199 K. We also calculate electronic in-plane distributions, which are far from thermal, and show that subband electron temperatures can be hundreds to thousands of degrees higher than the heat sink. Finally, we emphasize the role of coherent tunneling current by looking at the size of coherences, the off-diagonal elements of the density matrix. At the design lasing field, efficient injection manifests itself in a large injector/upper lasing level coherence, which underscores the insufficiency of semiclassical techniques to address injection in QCLs.

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Section: Resultsmentioning

confidence: 90%

Quantum Transport Simulation of High-Power 4.6-μm Quantum Cascade Lasers

et al. 2016

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“…However, in plane dynamics included in this method, usually inaccessible with other approaches, not only yields the higher level of accuracy but also reveals features that were hidden so far. While the latter were discussed in [25] in this paper we concentrate on the presentation of the results that illustrate fundamentals of mid-IR QCLs operation and give quantitative estimates of important QCL characteristics. For the illustration of the calculation method we have selected results obtained for the structure of Refs.…”

Section: Figurementioning

confidence: 99%

Mid-IR quantum cascade lasers: Device technology and non-equilibrium Green's function modeling of electro-optical characteristics

Bugajski

Gutowski

Karbownik

et al. 2014

Phys. Status Solidi B

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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.

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“…3 were used to calculate electronic transport and optical gain in QCL emitting at ffi 5 lm (hm ffi 0:25 eV), designed by Evans et al (2007). The equations of the NEGF formalism were solved for one QCL module with the contact self-energies which mimic periodic boundary conditions (Haldas et al 2011;Kolek et al 2012). Other self-energies included into formalism represent electron-phonon (LO, LA), interface roughness, alloy disorder and ionized impurity scatterings.…”

Section: Quantum Cascade Lasermentioning

confidence: 99%