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

Tzveta T. Apostolova; Andrey A. Ionin; Sergej Ivanovich Kudryashov; Leonid V. Seleznev; Dmitriy V. Sinitsyn

doi:10.1117/1.OE.51.12.121808

3 August 2012 Self-limited ionization in bandgap renormalized GaAs at high femtosecond laser intensities

Tzveta T. Apostolova, Andrey A. Ionin, Sergej Ivanovich Kudryashov, Leonid V. Seleznev, Dmitriy V. Sinitsyn

Author Affiliations +

Optical Engineering, Vol. 51, Issue 12, 121808 (August 2012). https://doi.org/10.1117/1.OE.51.12.121808

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.

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Tzveta T. Apostolova, Andrey A. Ionin, Sergej Ivanovich Kudryashov, Leonid V. Seleznev, and Dmitriy V. Sinitsyn "Self-limited ionization in bandgap renormalized GaAs at high femtosecond laser intensities," Optical Engineering 51(12), 121808 (3 August 2012). https://doi.org/10.1117/1.OE.51.12.121808

Published: 3 August 2012

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