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Using Microwave and Macroscopic Samples of Dielectric Solids to Study the Photonic Properties of Disordered Photonic Bandgap Materials
Published on: September 26, 2014
Light-induced gaps in semiconductor band-to-band transitions
1Institut für Theoretische Physik, Universität Frankfurt, 60054 Frankfurt am Main, Germany.
Physical Review Letters
|July 13, 2004
Summary
Researchers observed a two-band Mollow triplet in gallium arsenide (GaAs) thin films. This phenomenon arises from light-induced band gaps caused by coherent band mixing under intense ultrashort laser pulses.
Area of Science:
- Solid-state physics
- Quantum optics
- Materials science
Background:
- Semiconductor band gaps are fundamental to their optical properties.
- Ultrafast laser excitation can induce novel phenomena in semiconductors.
- The Mollow triplet is a known spectral feature in atomic systems.
Purpose of the Study:
- To investigate spectral features in thin gallium arsenide (GaAs) films under intense ultrashort laser pulses.
- To interpret the origin of observed spectral structures.
- To explore coherent band mixing effects in semiconductors.
Main Methods:
- Excitation of 50-100 nm thin GaAs films using 5 fs pulses at 3 x 10^12 W/cm^2.
- Analysis of the optical spectrum to identify peak structures.
- Comparison with solutions of the semiconductor Bloch equations.
Main Results:
- Observation of a triplet structure around the third harmonic of the semiconductor band gap.
- Interpretation of the triplet as a two-band Mollow triplet.
- Attribution of the triplet to light-induced band gaps from coherent band mixing.
Conclusions:
- Coherent band mixing under intense laser fields leads to a two-band Mollow triplet in GaAs.
- The observed spectral feature provides evidence for light-induced band gaps.
- The theoretical framework accounts for full tight-binding bands without rotating-wave approximation.
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