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Optical Engineering

Self-limited ionization in bandgap renormalized GaAs at high femtosecond laser intensities
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Paper Abstract

Theoretical modeling of photo-induced electron-hole plasma and bandgap dynamics in GaAs at high femtosecond laser intensities ( ∼ TW/cm2) employing a quantum kinetic formalism based on a generalized Boltzmann-type equation, predicts for the first time against expectations, the saturation of plasma densities despite the strong direct bandgap narrowing. Though the transient electronic bandgap renormalization provides a significant positive feedback for all relevant single-photon and impact ionization mechanisms, which is clearly observable at moderate (sub-TW/cm2) laser intensities, the counterintuitive plasma density saturation at higher laser intensities and high plasma densities ( ∼ 1022  cm−3) is dictated by much stronger negative feedback, originating from a highly-nonlinear transient enhancement of the corresponding Auger recombination coefficient for the shrinking bandgap. These theoretical predictions are in semi-quantitative agreement with the results of our time-resolved reflectivity infrared (IR)-pump experiments, which support this newly predicted process of self-limiting ionization dynamics in strongly photo-excited semiconductors, such as GaAs, with induced bandgap shrinkage.

Paper Details

Date Published: 3 August 2012
PDF: 17 pages
Opt. Eng. 51(12) 121808 doi: 10.1117/1.OE.51.12.121808
Published in: Optical Engineering Volume 51, Issue 12
Show Author Affiliations
Tzveta T. Apostolova, Institute of Nuclear Research and Nuclear Energy (Bulgaria)
Andrey A. Ionin, P.N. Lebedev Physical Institute (Russian Federation)
Sergej Ivanovich Kudryashov, P.N. Lebedev Physical Institute (Russian Federation)
Leonid V. Seleznev, P.N. Lebedev Physical Institute (Russian Federation)
Dmitriy V. Sinitsyn, P.N. Lebedev Physical Institute (Russian Federation)

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