Random lasing from dye-doped chiral nematic liquid crystals in oriented and non-oriented cells
Random lasing from dye-doped chiral nematic liquid crystals in oriented and non-oriented cells
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DOI：
10.1140/epjb/e2013-30822-0
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发表时间：
2013-03
期刊：
影响因子：
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通讯作者：
Longwu Li;L. Deng
中科院分区：
文献类型：
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作者：
Longwu Li;L. Deng
这些是描述染料掺杂手性液晶中随机激光的实验结果。本文研究了一种新的基于染料掺杂手性液晶螺旋畴的无规激光发射。在倍频532 nm Nd：YAG（钇铝石榴石）激光泵浦光激发下，仔细观察和分析了染料掺杂手性双折射液晶在600 ~ 620 nm波长范围内的随机激射。此外，多模峰的线宽小于0.2nm。在取向和非取向单元中的两种随机激光行为之间的差异源于这样的事实，即在取向单元中出现的随机激光产生于由液晶分子的螺旋域产生的光的更强的多重散射。此外，具有不同取向的手性双列相液晶微区可以引起扩散常数的变化，从而导致随机激光器的激光强度的减小或增大，以及其能量阈值的增大或减小。此外，还对两种实验结果进行了详细的比较，给出了激光阈值和激光模数与输运平均自由程、激发面积和样品尺寸的关系。这个过程允许我们通过改变样品的结构来获得随机激光，以低成本实现可调谐随机激光。
These are the experimental results describing random lasing in dye-doped chiral nematic liquid crystals. A novel random lasing emission is studied in this article based on the helical domains of dye-doped chiral nematic liquid crystals in oriented and non-oriented cells. Under frequency doubled 532 nm Nd:YAG (yttrium aluminum garnet) laser-pumped optical excitation, we carefully observed and analysed random lasing from dye-doped chiral nematic liquid crystals with wavelength ranges from 600 nm to 620 nm. In addition, the line-width of multi-mode peaks is less than 0.2 nm. The difference between the two random lasing behaviours in the oriented and non-oriented cells arises from the fact that random lasing appearing in the oriented cell results from stronger multiple scattering of light generated by the spiral domains of the liquid crystal molecules. Furthermore, chiral nematic liquid crystal micro-domains with different orientations can induce variation of the diffusion constant, thereby resulting in a decrease or increase in the lasing intensity of the random lasers, and an increase or decrease in their energy thresholds. In addition, a detailed comparison of the two experimental results is also presented in the article, showing the dependence of the lasing threshold and the number of lasing modes on the transport mean free path, the excited area, and the sample size. This process allows us to obtain a random laser by changing the structure of the sample, realising tunable random lasers at low cost.