Browsing by Author "Lin, Jia-De"

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Multi-wavelength laser tuning based on cholesteric liquid crystals with nanoparticles
(2016-04-27)
Chen, Sheng-Chieh
;
Lin, Jia-De
;
Lee, Chia-Rong
;
Hwang, Shug-June
;
影像與生醫光電研究所
A controllable multi-wavelength laser from a dye-doped cholesteric liquid crystal (DDCLC) cell is demonstrated by incorporating self-assembled polyhedral oligomeric silsesquioxane (POSS) nanoparticles (NPs). Multi-wavelength lasing emission is achieved by formation of multiple planar domains; this formation is dominantly influenced by the vertical alignment of NP clusters adsorbed on the substrate surface through a rapid thermal annealing process. The multi-wavelength lasing peaks are generated through the resultant effect of multiple longitudinal resonant modes of a Fabry-Perot etalon between the cell substrates and the amplification of fluorescence photons with the resonant wavelengths within the broadening long-wavelength edge of the reflection band of the multi-domain CLC. The amount of multi-wavelength lasing peaks can be controlled by changing the POSS NP concentration and the cooling rate of the cell. Furthermore, thermo-reversible control of the multi-wavelength lasing emission can be attained by controlling the thermally induced phase separation process of the POSS/DDCLC cell via a heating/cooling cyclic process.
Ultralow-threshold single-mode lasing based on a one-dimensional asymmetric photonic bandgap structure with liquid crystal as a defect layer
(2014-06-15)
Wang, Hsiao-Tsung
;
Lin, Jia-De
;
Lee, Chia-Rong
;
Lee, Wei
;
光電學院
In this Letter, we propose defect-mode lasing from a one-dimensional asymmetric photonic structure with dye-doped nematic liquid crystal as a central defect layer. The local field intensity of the distinguished single defect mode at the overlapped photonic band edges is drastically enhanced by the asymmetric structure consisting of two distinct multilayer photonic crystals. With high density of states of photons, effective output lasing emission and maximum input excitation are ensured. As a result, the single-mode lasing with a low excitation threshold of 0.2 mu J/pulse is achieved due to the combination of the defect layer and the photonic band edge effect. (C) 2014 Optical Society of America