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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 23 — Nov. 18, 2013
  • pp: 27804–27815

Importance of the microscopic effects on the linewidth enhancement factor of quantum cascade lasers

Tao Liu, Kenneth E. Lee, and Qi Jie Wang  »View Author Affiliations

Optics Express, Vol. 21, Issue 23, pp. 27804-27815 (2013)

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Microscopic density matrix analysis on the linewidth enhancement factor (LEF) of both mid-infrared (mid-IR) and Terahertz (THz) quantum cascade lasers (QCLs) is reported, taking into account of the many body Coulomb interactions, coherence of resonant-tunneling transport and non-parabolicity. A non-zero LEF at the gain peak is obtained due to these combined microscopic effects. The results show that, for mid-IR QCLs, the many body Coulomb interaction and non-parabolicity contribute greatly to the non-zero LEF. In contrast, for THz QCLs, the many body Coulomb interactions and the resonant-tunneling effects greatly influence the LEF resulting in a non-zero value at the gain peak. This microscopic model not only partially explains the non-zero LEF of QCLs at the gain peak, which observed in the experiments for a while but cannot be explicitly explained, but also can be employed to improve the active region designs so as to reduce the LEF by optimizing the corresponding parameters.

© 2013 Optical Society of America

OCIS Codes
(140.0140) Lasers and laser optics : Lasers and laser optics
(140.3070) Lasers and laser optics : Infrared and far-infrared lasers
(140.5965) Lasers and laser optics : Semiconductor lasers, quantum cascade

ToC Category:
Lasers and Laser Optics

Original Manuscript: July 5, 2013
Revised Manuscript: October 29, 2013
Manuscript Accepted: October 29, 2013
Published: November 6, 2013

Tao Liu, Kenneth E. Lee, and Qi Jie Wang, "Importance of the microscopic effects on the linewidth enhancement factor of quantum cascade lasers," Opt. Express 21, 27804-27815 (2013)

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