GaAs quantum box cascade lasers

Becker, C.; Sirtori, Carlo; Drachenko, O.; Rylkov, V. V.; Smirnov, Dmitry; Leotin, J.

doi:10.1063/1.1515135

Cited by 64 publications

(46 citation statements)

References 13 publications

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“…A strong magnetic field applied along the growth axis of a QCL quantizes the lateral motion in terms of Landau levels. Their energy tuning with magnetic field has been shown to be responsible for modulation of the level lifetimes 8,9 , allowing to demonstrate lasing up to higher temperature (225 K in ref. 10 ) than in usual THz QCLs (199 K in ref.…”

Section: Nanowire Terahertz Quantum Cascade Lasersmentioning

confidence: 99%

Nanowire terahertz quantum cascade lasers

Grange

2014

Applied Physics Letters

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Quantum cascade lasers made of nanowire axial heterostructures are proposed. The dissipative quantum dynamics of their carriers is theoretically investigated using non-equilibrium Green functions. Their transport and gain properties are calculated for varying nanowire thickness, from the classical-wire regime to the quantum-wire regime. Our calculation shows that the lateral quantum confinement provided by the nanowires allows an increase of the maximum operation temperature and a strong reduction of the current density threshold compared to conventional terahertz quantum cascade lasers.Quantum cascade lasers (QCLs) 1 are semiconductor unipolar devices emitting coherent infrared radiation. Their active regions consist of stacked planar quantum wells (QWs) forming a superlattice along the growth direction. At first sight, a large part of the physical properties of QCLs can be qualitatively understood in a onedimensional picture, in particular for quantum confinement, tunneling processes and radiative transitions. Nevertheless, the free in-plane motion of the carriers provides a continuous energy reservoir (i.e. subbands) which plays a major role in the energy and phase relaxation processes. For QCLs operating in the terahertz (THz) range 2,3 , due to the relatively small energy separation between the subbands associated with the lasing levels, the non-radiative scattering processes are very efficient and are responsible for intrinsic limitations in terms of quantum efficiency and maximum operation temperature.Reducing the dimensionality of electronic systems is generally a way to increase the carrier lifetimes 4-7 . A strong magnetic field applied along the growth axis of a QCL quantizes the lateral motion in terms of Landau levels. Their energy tuning with magnetic field has been shown to be responsible for modulation of the level lifetimes 8,9 , allowing to demonstrate lasing up to higher temperature (225 K in ref. 10 ) than in usual THz QCLs (199 K in ref. 11 ). However, Landau levels remain highly degenerate so that their ideal discrete density of states is strongly broadened by disorder effects 12 . On the other hand, QCLs based on 0D nanostructures such as self-assembled or lithographically defined quantum dots (QDs) have been proposed [13][14][15][16] in order to achieve low threshold current and high operation temperature. However, a direct comparison of the device performances with respect to conventional THz QCLs is lacking, and the intermediate regime between the limiting cases coupled 0D QDs and coupled 2D QWs remains to be investigated.In this letter we propose QCLs based on nanowire (NW) superlattice heterostructures. Using the formalism of non-equilibrium Green functions (NEGF), we calculate charge transport and THz gain in laterally-quantized quantum cascade (QC) structures. We investigate the dynamics of charge carriers in QC structures having lateral dimensionality ranging from 2D to 0D, providing a direct comparison of NW QCLs and conventional QCLs. Quantum cascade lasers made of nanowire axia...

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Section: Nanowire Terahertz Quantum Cascade Lasersmentioning

confidence: 99%

Nanowire terahertz quantum cascade lasers

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2014

Applied Physics Letters

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“…The highest operating temperature of 225K is reported for resonant-phonon design scheme assisted by external magnetic field for additional carrier confinement [3]. The role of the magnetic field is to suppress non-radiative intersubband relaxation processes and thus increase the optical gain [1,3,[8][9][10][11][12][13][14][15][16][17][18]. Hence, detailed understanding of various scattering mechanisms, * corresponding author; e-mail: radovanovic@etf.bg.ac.rs relevant for laser operation, may be an important factor in improving its performance.…”

Section: Introductionmentioning

confidence: 99%

Inter-Landau Level Scattering Processes in Magnetic Field Assisted THz Quantum Cascade Laser

et al. 2011

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We present a detailed analysis of GaAs/AlGaAs terahertz quantum cascade laser in the presence of an intense external magnetic field. One of the objectives in further development of THz quantum cascade laser is the realization of structures operating at higher temperatures. This is difficult to obtain as the operating photon emission energy is smaller than the longitudinal-optical phonon energy in the semiconductor material. With increased temperature, electrons in the upper radiative state gain sufficient in-plane energy to emit an longitudinal-optical phonon, which represents a non-radiative scattering and reduces the optical gain. By applying strong magnetic field, two-dimensional continuous energy subbands become split into series of discrete Landau levels, and at particular values of B it is possible to quench these non-radiative channels. Numerical simulations are performed on two-well design quantum cascade laser operating at 4.6 THz, implemented in GaAs/Al0.15Ga0.85As, and the magnetic field is perpendicular to the epitaxial layers. Strong oscillations of carrier lifetimes for the upper state of the laser transition, as a function of magnetic field are observed, which can be attributed to interface roughness scattering and longitudinal-optical phonon scattering between Landau levels.

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“…An intense magnetic field applied perpendicular to the 2DEG planes of a QCL causes two-dimensional continuous energy subbands to split into series of discrete Landau levels (LLs). Since the arrangement of Landau levels depends strongly on the magnitude of the magnetic field, this enables one to control the population inversion in the active region, and hence the optical gain [14][15][16][17]. Furthermore, strong effects of band nonparabolicity result in subtle changes of the lasing wavelength at magnetic fields which maximize the gain, thus providing a path for fine-tuning of the output radiation.…”

Section: Introductionmentioning

confidence: 99%

Quantum Cascade Laser Design for Tunable Output at Characteristic Wavelengths in the Mid-Infrared Spectral Range

et al. 2010

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We present a method for systematic optimization of quantum cascade laser active region, based on the use of the genetic algorithm. The method aims at obtaining a gain-maximized structure, designed to emit radiation at specified wavelengths suitable for direct absorption by pollutant gasses present in the ambient air. After the initial optimization stage, we introduce a strong external magnetic field to tune the laser output properties and to slightly modify the emission wavelength to match the absorption lines of additional compounds. The magnetic field is applied perpendicularly to the epitaxial layers, thus causing two-dimensional continuous energy subbands to split into series of discrete Landau levels. This affects all the relevant relaxation processes in the structure and consequently the lifetime of carriers in the upper laser level. Furthermore, strong effects of band nonparabolicity result in subtle changes of the lasing wavelength at magnetic fields which maximize the gain, thus providing a path for fine-tuning of the output radiation properties. Numerical results are presented for GaAs/Al x Ga 1−x As based quantum cascade laser structures designed to emit at particular wavelengths in the mid-infrared part of the spectrum.

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GaAs quantum box cascade lasers

Cited by 64 publications

References 13 publications

Nanowire terahertz quantum cascade lasers

Nanowire terahertz quantum cascade lasers

Inter-Landau Level Scattering Processes in Magnetic Field Assisted THz Quantum Cascade Laser

Quantum Cascade Laser Design for Tunable Output at Characteristic Wavelengths in the Mid-Infrared Spectral Range

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