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Random lasing in ballistic and diffusiveregimes for macroporous silica-based systems with tunable scattering
Xiangeng Meng1, Koji Fujita, Shunsuke Murai
1Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku 615-8510, Kyoto, Japan.
Optics Express
|July 1, 2010
Summary
Researchers explored random lasing in a dye-infused silica system by tuning solvent refractive index. They observed random lasing with coherent feedback in two scattering regimes, influenced by microcavities and amplified modes.
Area of Science:
- Photonics and optical physics.
- Materials science and nanotechnology.
Background:
- Random lasing offers potential for low-cost coherent light sources.
- Controlling scattering in gain media is crucial for understanding lasing mechanisms.
Purpose of the Study:
- To systematically investigate random lasing properties in weakly scattering systems.
- To explore the influence of refractive index contrast on coherent feedback in random lasers.
Main Methods:
- Utilizing a macroporous silica disk immersed in a tunable dye-alcohol mixture solvent.
- Varying the solvent's refractive index to control scattering strength.
- Analyzing emission spectra for sharp spectral spikes indicative of random lasing with coherent feedback.
Main Results:
- Observed random lasing with coherent feedback in two distinct scattering regimes.
- Coherent feedback was present in very weakly scattering (nearly transparent) systems.
- Feedback vanished at a critical refractive index contrast and reappeared with further increases.
Conclusions:
- Microcavities are crucial for coherent feedback in the ballistic (very weak scattering) regime.
- Amplified extended modes may contribute to coherent feedback as scattering strength increases.
- Tunable refractive index offers a method to control random lasing phenomena.
