Electron-lattice coupling in bound-to-continuum THz quantum-cascade lasers

Vitiello, Miriam S.; Scamarcio, Gaetano; Spagnolo, Vincenzo; Losco, Tonia; Green, Richard P.; Tredicucci, Alessandro; Beere, Harvey E.; Ritchie, D. A.

doi:10.1063/1.2211301

Cited by 40 publications

(33 citation statements)

References 17 publications

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“…3͑b͒ shows that the most likely channel for thermal activation of electrons out of the upper laser level is into the higher lying state localized mainly in the first two wells of the miniband; previous photoluminescence studies of operating QCLs have supported the suggestion of carrier leakage into this state. 24 The measured activation energy is in reasonable agreement with the calculated position of this level ϳ7.5 meV above the upper laser level.…”

Section: Temperature Dependencesupporting

confidence: 73%

Gain recovery dynamics of a terahertz quantum cascade laser

et al. 2009

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The gain recovery time of a bound-to-continuum terahertz quantum cascade laser is measured using a stimulated emission photocurrent technique. At low temperatures a value ϳ50 ps is found. This tends to decrease with rising temperature, and suggests that class B laser dynamics should be expected from these devices. Both the value and the trend in the gain recovery time are found to be consistent with hopping transport through the miniband. Power-dependent measurements of the photocurrent clearly show the effects of inhomogeneous broadening of the gain transition.

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Section: Temperature Dependencesupporting

confidence: 73%

Gain recovery dynamics of a terahertz quantum cascade laser

et al. 2009

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“…If thermalization of carriers by e-e intrasubband scattering is not significantly more efficient than intersubband scattering processes, the carriers accumulate in the subband 1 up to the kinetic energy of 9 meV, in contrast to the Fermi-Dirac or the Maxwell-Boltzmann distributions 35,36 . The relative simplicity of this device would make it a good candidate for studies of electron temperature by microprobe photoluminescence experiments 37 .…”

Section: Resultsmentioning

confidence: 99%

A phonon scattering assisted injection and extraction based terahertz quantum cascade laser

Dupont

Fathololoumi

Wasilewski

et al. 2012

Journal of Applied Physics

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A novel lasing scheme for terahertz quantum cascade lasers, based on consecutive phonon-photon-phonon emissions per module, is proposed and experimentally demonstrated. The charge transport of the proposed structure is modeled using a rate equation formalism. An optimization code based on a genetic algorithm was developed to find a four-well design in the GaAs/Al 0.25 Ga 0.75 As material system that maximizes the product of population inversion and oscillator strength at 150 K. The fabricated devices using Au double-metal waveguides show lasing at 3.2 THz up to 138 K. The electrical characteristics display no sign of differential resistance drop at lasing threshold, which suggests -thanks to the rate equation model -a slow depopulation rate of the lower lasing state, a hypothesis confirmed by non-equilibrium Green's function calculations.

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“…In the case of BTC devices, band-to-band transitions associated with the injector low energy miniband and upper laser level j = 2 are visible, together with the heavyhole (HH) and light-hole (LH) exciton peaks arising from level 2, as expected from the calculation of the Debye screening length [8,9]. For the line shape analysis we used as fitting function a Lorentzian on the low energy side joined with an exponential decay on the high energy side for band-to-band transitions and a Lorentzian for the exciton peaks [10,11]. The experimental data have been fitted leaving T j e , the band intensities and the full width at half maximum of the HH and LH exciton peaks as fitting parameters.…”

Section: Resultsmentioning

confidence: 99%

Experimental Investigation of Hot Carriers in Terahertz Quantum Cascade Lasers

2008

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The nature of the electron distribution and the electron-lattice energy relaxation phenomena in all classes of quantum cascade lasers operating in the THz range, namely, resonant-phonon, bound-to-continuum, and interlaced photon-phonon designs are reviewed. Thermalized hot-electron distributions are found in all cases. However, electronic temperatures of individual conduction subband are strongly influenced by the specific quantum design and the actual electron-lattice energy relaxation channels. A wealth of information was obtained both below and above laser threshold from the analysis of micro-probe band-to-band photoluminescence spectra recorded with a spatial resolution of ≈ 2 µm. The influence of the detailed knowledge of the hot electron distributions on the design of improved THz quantum cascade lasers aiming at high temperature operation will be discussed.

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Electron-lattice coupling in bound-to-continuum THz quantum-cascade lasers

Abstract: Articles you may be interested inSubband electronic temperatures and electron-lattice energy relaxation in terahertz quantum cascade lasers with different conduction band offsets

Cited by 40 publications

References 17 publications

Gain recovery dynamics of a terahertz quantum cascade laser

Gain recovery dynamics of a terahertz quantum cascade laser

A phonon scattering assisted injection and extraction based terahertz quantum cascade laser

Experimental Investigation of Hot Carriers in Terahertz Quantum Cascade Lasers

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