Electron Transport and Terahertz Gain in Quantum-Dot Cascades

Vukmirović, Nenad; Indjin, D.; Ikonić, Z.; Harrison, P.

doi:10.1109/lpt.2007.912533

Cited by 20 publications

(14 citation statements)

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“…[26][27][28][29]. In these works, the electron-phonon interaction is accounted for by a phonon Greens function which enters into the electron self-energy; it is therefore represented as an average field which is assumed to remain at thermal equilibrium.…”

Section: Electron-lo-phonon Couplingmentioning

confidence: 99%

“…The most detailed approach involves nonequilibrium Green's function (NEGF) methods, which provide motivation for the lateral confinement approach, but are extremely computationally intensive and also tedious for the nonexpert [24][25][26][27][28][29]. Density matrix models are attractive since they allow intuitive use of quantum-cascade wave functions as a basis and have been shown to capture signatures of coherent electron tunneling as well as coherent response to the optical field [30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

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Density matrix model for polarons in a terahertz quantum dot cascade laser

Burnett

Williams

2014

Phys. Rev. B

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A density matrix based method is introduced for computation of steady-state dynamics in quantum cascade systems of arbitrary size, which incorporates an optical field coherently. The method is applied to a model terahertz quantum dot cascade laser system, where a means of treating coherent electron-optical-phonon coupling is also introduced. Results predict a strong increase in the upper state lifetime and operating temperature as compared to traditional well-based terahertz quantum cascade lasers. However, new complications also arise, including multiple peaks in the gain spectrum due to strong electron-phonon coupling, and strong parasitic subthreshold current channels that arise due to reduced dephasing. It is anticipated that novel design schemes will be necessary for such lasers to become a reality.

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Section: Electron-lo-phonon Couplingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Density matrix model for polarons in a terahertz quantum dot cascade laser

Burnett

Williams

2014

Phys. Rev. B

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“…35,36 The factor k in the summation, effective for non-nearest-neighbour scattering, originates from the scatterings from any QCL period left of the central period into any period right of it, or vice versa. Once again, we introduce the "tight-binding" approximation assuming that only the nearest neighbours interact, and set P ¼ 2.…”

Section: B the Self-consistent Rate Equation Modelmentioning

confidence: 99%

Genetic algorithm applied to the optimization of quantum cascade lasers with second harmonic generation

Gajic

Radovanović

Milanović

et al. 2014

Journal of Applied Physics

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A computational model for the optimization of the second order optical nonlinearities in GaInAs/AlInAs quantum cascade laser structures is presented. The set of structure parameters that lead to improved device performance was obtained through the implementation of the Genetic Algorithm. In the following step, the linear and second harmonic generation power were calculated by self-consistently solving the system of rate equations for carriers and photons. This rate equation system included both stimulated and simultaneous double photon absorption processes that occur between the levels relevant for second harmonic generation, and material-dependent effective mass, as well as band nonparabolicity, were taken into account. The developed method is general, in the sense that it can be applied to any higher order effect, which requires the photon density equation to be included. Specifically, we have addressed the optimization of the active region of a double quantum well In 0.53 Ga 0.47 As/Al 0.48 In 0.52 As structure and presented its output characteristics. V C 2014 AIP Publishing LLC. [http://dx

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“…This makes these approaches computationally quite demanding especially when a large number of electronic states is involved. The nonequilibrium Green function method has been applied recently to study the feasibility of a quantum dot terahertz quantum cascade laser [35]. The results that predict low threshold current and high optical gain appear quite promising.…”

Section: Transport Propertiesmentioning

confidence: 99%