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Bragg diffraction of microcavity polaritons by a surface acoustic wave
Kikuo Cho1, Kazunori Okumoto, N I Nikolaev
1Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka 560-8531, Japan.
Physical Review Letters
|August 11, 2005
Summary
This study shows that exciton states enhance polariton Bragg scattering via acoustic waves. This leads to multiple orders of diffracted light, unlike conventional acousto-optics.
Area of Science:
- Solid-state physics
- Optics
- Acoustics
Background:
- Polaritons are quasiparticles formed from the coupling of photons and excitons.
- Acousto-optic effects typically involve the interaction of light with acoustic waves.
- Exciton states play a crucial role in mediating light-matter interactions.
Purpose of the Study:
- To investigate Bragg scattering of polaritons mediated by coherent acoustic waves.
- To explore the enhancement of this scattering through resonant exciton states.
- To contrast this phenomenon with conventional acousto-optic effects.
Main Methods:
- Utilizing polaritons in Gallium Arsenide (GaAs) microcavities.
- Driving the system with a surface acoustic wave (SAW) at 1 GHz.
- Analyzing the resulting Bragg spectra to observe diffracted light orders.
Main Results:
- Strong enhancement of Bragg scattering observed due to resonant exciton states.
- Multiple orders of diffracted light (Bragg replicas up to n=3) were detected.
- An acoustically induced band gap of approximately 0.6 meV was measured.
Conclusions:
- Resonant exciton states significantly enhance polariton Bragg scattering by acoustic waves.
- This resonant enhancement leads to observable multiple diffraction orders, a departure from conventional acousto-optics.
- The findings demonstrate a novel mechanism for controlling light propagation using acoustic waves in microcavities.