Cyclic behavior of ultrafast self-modulation of the light-absorption spectrum under conditions of pump and stimulated emission in GaAs

Under picosecond photogeneration of charge carriers in GaAs, accompanied by intense stimulated emission of the semiconductor itself, ultrafast self-modulation of its light-absorption spectrum takes place, which consists in the appearance of regions of local absorption enhancement (bumps) in the spec...

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Bibliographic Details
Published in:Semiconductors (Woodbury, N.Y.) N.Y.), 2008-09, Vol.42 (9), p.1037-1043
Main Authors: Ageeva, N. N., Bronevoi, I. L., Krivonosov, A. N., Nalet, T. A.
Format: Article
Language:English
Subjects:
ABSORPTION
ABSORPTION SPECTRA
CHARGE CARRIERS
Conduction bands
Current carriers
Depletion
Electromagnetic absorption
Electronic and Optical Properties of Semiconductors
Energy distribution
ENERGY LEVELS
ENERGY SPECTRA
Fermi-Dirac statistics
GALLIUM ARSENIDES
Magnetic Materials
Magnetism
MATERIALS SCIENCE
MODULATION
Physics
Physics and Astronomy
SEMICONDUCTOR MATERIALS
STIMULATED EMISSION
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Summary:Under picosecond photogeneration of charge carriers in GaAs, accompanied by intense stimulated emission of the semiconductor itself, ultrafast self-modulation of its light-absorption spectrum takes place, which consists in the appearance of regions of local absorption enhancement (bumps) in the spectrum. The ultrafast self-modulation is found to exhibit a cyclic behavior; i.e., the pattern of the self-modulation of the spectrum (the number and spectral position of the bumps) is repeated after a certain time T c falling in the picosecond range. The cycle period T c varies over the time span of the pump pulse and depends on the pulse energy, which means that T c is a function of the pump intensity. Assuming that self-modulation of the absorption reflects self-modulation of the charge-carrier energy distribution in GaAs under pumping, experimental results can be formulated as follows: in the process of the ultrafast self-modulation, deviations of the occupancies of different energy levels from the Fermi distribution evolve with time in a mutually related way; the distribution of the occupancy depletion in the conduction band repeats cyclically in time; and the cycle period decreases as the intensity of the pump increases.
ISSN:1063-7826
1090-6479
DOI:10.1134/S1063782608090078