Nonequilibrium Dynamics in a Quasi-Two-Dimensional Electron Plasma after Ultrafast Intersubband Excitation

Lutgen, S.; Kaindl, Robert A.; Woerner, M.; Elsaesser, Thomas; Hase, A.; Künzel, H.; Gulia, M.; Meglio, Duilio; Lugli, Paolo

doi:10.1103/physrevlett.77.3657

Cited by 56 publications

(29 citation statements)

References 13 publications

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“…Scientifically and technologically important examples are the development of high-power MBE-and MOVPE-grown QCL operating in CW at room temperature and above [2]- [4], high-speed electrical modulation without relaxation oscillation [5] and observation of Bloch gain in QCLs [6], and the realization of QC structures emitting in the terahertz (THz) range of the spectrum [7], [8]. However, the mechanism of electronic transport across the active and injector regions, which is closely related to the dynamic gain recovery, has not been extensively investigated, though there have been some studies of carrier transport and relaxation processes in nonlasing quantum-well (QW) structures [9]- [12].…”

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confidence: 99%

Time-Resolved Investigations of Electronic Transport Dynamics in Quantum Cascade Lasers Based on Diagonal Lasing Transition

Choi

Diehl

et al. 2009

IEEE J. Quantum Electron.

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Abstract-In this study, the nature of electronic transport in quantum cascade lasers (QCLs) has been extensively investigated using an ultrafast time-resolved, degenerate, pump-probe optical technique. Our investigations enable a comprehensive understanding of the gain recovery dynamics in terms of a coupling of the electronic transport to the oscillating intracavity laser intensity. In QCLs that have a lasing transition diagonal in real space, studies of the near-threshold reveal that the transport of electrons changes bias region from phonon-limited relaxation (tens of picoseconds) below threshold to photon-driven transport via stimulated emission (a few picoseconds) above threshold. The gain recovery dynamics in the photon-driven regime is compared with conventional four-level lasers such as atomic, molecular, and semiconductor interband lasers. The depopulation dynamics out of the lower lasing state is explained using a tight-binding tunneling model and phonon-limited relaxation. For the superlattice relaxation, it is possible to explain the characteristic picosecond transport via dielectric relaxation; Monte Carlo simulations with a simple resistor model are developed, and the Esaki-Tsu model is applied. Subpicosecond dynamics due to carrier heating in the upper subband are isolated and appear to be at most about 10% of the gain compression compared with the contribution of stimulated emission. Finally, the polarization anisotropy in the active waveguide is experimentally shown to be negligible on our pump-probe data, supporting our interpretation of data in terms of gain recovery and transport.

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confidence: 99%

Time-Resolved Investigations of Electronic Transport Dynamics in Quantum Cascade Lasers Based on Diagonal Lasing Transition

Choi

Diehl

et al. 2009

IEEE J. Quantum Electron.

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“…The proposed scheme can thus be useful for realizing a tunable table-top source of intense MIR radiation, as well as for practical applications in many areas. [1][2][3][4] …”

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confidence: 98%

Strong mid-infrared radiation from self-guided fast electron bunch propagating along a grated target surface in laser-solid interaction

Kodama

2012

Physics of Plasmas

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Generation of 10 12 W=cm 2 Smith-Purcell radiation in the infrared (5À20 lm) regime from the interaction of high-density laser-produced MeV electrons is proposed. The electron bunch is produced by impinging an intense ultrashort laser pulse on a metallic target with a grated upper surface. Particle-in-cell simulation shows that the electron bunch can efficiently couple to the periodic structure through the quasistatic self-generated electric and magnetic fields there. An analytical model for predicting the dependence of the radiation intensity on the laser and grating parameters is also proposed. With appropriate laser and grating parameters, the proposed scheme provides a tunable source for intense radiation in the infrared regime. V C 2012 American Institute of Physics. [http://dx.

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“…Under weak excitation this intrasubband scattering is slowed for states close to and below the Fermi Level where the high occupation probabilities lead to Pauli blocking and Coulomb screening; this accounts for the comparatively long ͑ϳ2 ps͒ thermalization times seen in femtosecond pump-probe experiments. 16 The higher the sample excitation level, the broader the spread of the electron distribution in k II though and these blocking effects are felt further up the energy curve. This may explain the longer 12 ϳ2.1 ps times measured here compared with the 0.8 ps previously measured at weak excitation in the same sample.…”

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confidence: 98%

Nonequilibrium electron distributions in a three-subband InGaAs/InAlAs quantum well studied via double resonance spectroscopy

Serapiglia

Vodopyanov

Phillips

2000

Applied Physics Letters

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Midinfrared optical pumping of electrons from the ground (n=1) to the first excited (n=2) subband of the quantum well produces a strongly nonthermal electron distribution which is probed spectroscopically. Two sharp induced absorption peaks appear, associated with electrons which have scattered from the upper subband via longitudinal optical (LO) phonon emission and absorption. The presence of the phonon absorption channel evidences the importance of nonequilibrium LO phonon populations (nph∼1), and the impact on the nonradiative intersubband scattering rates in quantum cascade laser devices is explored.

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Nonequilibrium Dynamics in a Quasi-Two-Dimensional Electron Plasma after Ultrafast Intersubband Excitation

Cited by 56 publications

References 13 publications

Time-Resolved Investigations of Electronic Transport Dynamics in Quantum Cascade Lasers Based on Diagonal Lasing Transition

Time-Resolved Investigations of Electronic Transport Dynamics in Quantum Cascade Lasers Based on Diagonal Lasing Transition

Strong mid-infrared radiation from self-guided fast electron bunch propagating along a grated target surface in laser-solid interaction

Nonequilibrium electron distributions in a three-subband InGaAs/InAlAs quantum well studied via double resonance spectroscopy

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