Gain recovery dynamics and photon-driven transport in quantum cascade lasers

Hyunyong Choi, Laurent Diehl, Zong Kwei Wu, Marcella Giovannini, Jérôme Faist, Federico Capasso, Theodore B. Norris

Research output: Contribution to journalArticlepeer-review

83 Citations (Scopus)


Quantum cascade lasers are semiconductor devices based on the interplay of perpendicular transport through the heterostructure and the intracavity lasing field. We employ femtosecond time-resolved pump-probe measurements to investigate the nature of the transport through the laser structure via the dynamics of the gain. The gain recovery is determined by the time-dependent transport of electrons through both the active regions and the superlattice regions connecting them. As the laser approaches and exceeds threshold, the component of the gain recovery due to the nonzero lifetime of the upper lasing state in the active region shows a dramatic reduction due to the onset of quantum stimulated emission; the drift of the electrons is thus driven by the cavity photon density. The gain recovery is qualitatively different from that in conventional lasers due to the superlattice transport in the cascade.

Original languageEnglish
Article number167401
JournalPhysical review letters
Issue number16
Publication statusPublished - 2008 Apr 24

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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