Dye-concentration-dependent lasing behaviors and spectral characteristics of cholesteric liquid crystals
Dye-concentration-dependent lasing behaviors and spectral characteristics of cholesteric liquid crystals
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DOI：
10.1007/s00340-013-5628-6
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发表时间：
2014-06
期刊：
影响因子：
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通讯作者：
Zhongyang Wang;C. Yang;Wensong Li;Lu-Jian Chen;Xiaozhong Wang;Z. Cai
中科院分区：
文献类型：
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作者：
Zhongyang Wang;C. Yang;Wensong Li;Lu-Jian Chen;Xiaozhong Wang;Z. Cai
研究了在532 nm泵浦下，不同染料掺杂浓度的双折射液晶的激光行为和光谱变化。结果表明，随着染料浓度的增加，长波长带边和激光线均发生了超过21 nm的蓝移。检测了圆偏振荧光光谱，并确定了圆偏振反转的位置与离散的激光谱线很好地吻合。蓝移可以归因于染料掺杂的双折射液晶的平均折射率和螺距的减小。斜率效率和阈值能量与染料浓度的关系可以归因于光子阻带的移动和激发穿透深度的变化。泵浦光的温度和入射角对激光输出特性也有很大的影响。在30.5 °C、10°入射角下，染料的最佳浓度为0.5wt%。在14.3 μJ的阈值能量以上，获得了601.4nm的激光发射，斜率效率为4%。
The laser behavior and spectral changes occurring in cholesteric liquid crystals with varying dye-doped concentrations were investigated when pumped at 532 nm. It was found that the long-wavelength band edge and the laser line exhibit a blue shift over 21 nm with increasing dye concentration. The circularly polarized fluorescence spectra were examined, and the location of the sense reversion of circular polarization was determined to coincide well with the discrete lasing lines. The blue shift can be ascribed to the decrease in average refractive index and pitch of the dye-doped cholesteric liquid crystals. The dependence of the slope efficiency and threshold energy on the dye concentration can be attributed to the shift in photonic stopband and the change in penetration depth of excitation. The temperature and incident angle of pumping beam also have a significant impact on the lasing properties. The optimal dye concentration is found to be 0.5 wt% at 30.5 °C with an incident angle of 10°. The laser emission located at 601.4 nm with slope efficiency of 4 % was achieved above the threshold energy of 14.3 μJ.