Surface Plasmon Enhanced Lasing in Cholesteric Liquid Crystals
| Autor: | Cheng-Yu Shih, 施政宇 |
|---|---|
| Rok vydání: | 2012 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 100 With a self-organized chiral structure, cholesteric liquid crystal is regarded as apromising one-dimensional photonic crystal. Cholesteric liquid crystals in the planner phase are materials with one-dimensional photonic band gap. Fluorescent emission in these materials is suppressed in the photonic band while enhanced at the band edges. This gain enhancement and distributed feedback effect can give rise to low threshold and mirrorless lasing at the photonic band edges of cholesteric liquid crystals. In the experiments, a layer with Ag nanoparticles is produced on the glass by plasma sputtering and thermal annealing for the purpose of enhancing fluorescence and lasing intensity. The experimental result indicates that the fluorescence and lasing intensity in Ag nanoparticles doped cholesteric liquid crystal cell can be enhanced one and a half times and seven times, respectively. This enhancement in the lasing intensity is attributed to the coupling of localized surface plasmon resonance from the Ag nanoparticles with the laser dye molecules, resulting in the increase in excitation and emission rate of the dye molecules in the localized electromagnetic field. Thus, this study demonstrates a cholesteric liquid crystal laser device with increased lasing pumping efficiency and reduced lasing energy threshold. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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