Tunable terahertz amplification in optically excited biased semiconductor superlattices: Influence of excited excitonic states

Dawei Wang, Aizhen Zhang, Lijun Yang, and Marc M. Dignam
Phys. Rev. B 77, 115307 – Published 7 March 2008

Abstract

We simulate the coherent carrier dynamics of an optically excited, undoped AlGaAs superlattice in the presence of a terahertz pulse using an excitonic formalism that includes 1s excitonic states as well as higher in-plane excited states and allows for dephasing and population decay. We show that this system exhibits tunable terahertz gain due to excitonic effects, even in the presence of a large number of unbound excitons. We find that gain coefficients greater than 20cm1 can be achieved over a tuning range of 311THz and that due to the coherent cascading of the carriers down the excitonic Wannier-Stark ladder, the gain coefficients have much higher gain saturation fields than comparable two-level systems.

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  • Received 2 November 2007

DOI:https://doi.org/10.1103/PhysRevB.77.115307

©2008 American Physical Society

Authors & Affiliations

Dawei Wang1, Aizhen Zhang1, Lijun Yang2, and Marc M. Dignam1

  • 1Department of Physics, Queen’s University, Kingston, Ontario, Canada K7L 3N6
  • 2Chemistry Department, University of California, Irvine, California 92697-2025, USA

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Vol. 77, Iss. 11 — 15 March 2008

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