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Quasi-phase-matched second-harmonic generation from asymmetric coupled quantum wells
Optics Letters
|October 22, 2009
Summary
Researchers achieved optical second-harmonic generation in asymmetric coupled GaAs quantum wells. This novel superlattice structure enhanced visible light generation by 3.6 times compared to homogeneous GaAs, demonstrating efficient quasi-phase matching.
Area of Science:
- Optics and Photonics
- Materials Science
- Semiconductor Physics
Background:
- Second-harmonic generation (SHG) is a key nonlinear optical process.
- Superlattices offer unique properties for nonlinear optics.
- Asymmetric quantum wells are crucial for efficient SHG.
Purpose of the Study:
- To measure optical second-harmonic generation in a superlattice of asymmetric coupled GaAs quantum wells for the first time.
- To demonstrate quasi-phase matching in such a structure.
- To quantify the enhancement in SHG intensity compared to a homogeneous material.
Main Methods:
- Fabrication of a superlattice with periodically reversed asymmetric GaAs quantum wells.
- Excitation of the superlattice with a lambda = 1.319 microm fundamental laser in reflection geometry.
- Measurement of the generated second-harmonic signal intensity and susceptibility.
Main Results:
- First-time measurement of optical SHG in asymmetric coupled GaAs quantum wells.
- Achieved quasi-phase matching by reversing quantum well orientation.
- Observed a 3.6-fold increase in SHG intensity compared to homogeneous GaAs.
Conclusions:
- The engineered superlattice effectively enhances visible light generation via SHG.
- Quasi-phase matching in asymmetric coupled quantum wells is a viable strategy for nonlinear optics.
- This work opens avenues for advanced photonic devices.
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