Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 46: Ultra-fast phenomena

HL 46.11: Vortrag

Freitag, 5. April 2019, 12:15–12:30, H31

Higher-order contributions and non-perturbative effects in the nonlinear optical absorption of direct-gap semiconductors — •Wolf-Rüdiger Hannes and Torsten Meier — Department of Physics and CeOPP, University of Paderborn, Warburger Str. 100, D-33098 Paderborn, Germany

The semiconductor Bloch equations including the intraband acceleration [1] are used to study the nonlinear absorption of single or multiple light pulses by direct-gap semiconductors. The steady state response can be described analytically by multi-photon absorption coefficients, which are shown to agree well with numerical results for short pulses and/or finite dephasing and relaxation times. The dependencies on the light frequencies, band gap energy, initial populations, and the time delay between the pulses are analyzed. In third order we confirm some previously described aspects [2] such as the strong enhancement of two-photon absorption for non-degenerate light frequencies. In higher orders we discuss both multi-photon absorption and dispersive corrections to lower orders. Beyond the perturbative treatment of the Bloch equations we investigate the intensity-dependent optical absorption for a single incident pulse and in a pump-probe setup.
[1] H. T. Duc, T. Meier, and S. W. Koch, Phys. Rev. Lett. 95, 086606 (2005).
[2] C. Aversa et al., Phys. Rev. B 50, 18073 (1994).