Wang Xiaofeng, Chang Shengli, Yang Jiankun, Zhou Mu, Cao Dingxiang, Tan Jichun
College of Opto-Electronic Science and Engineering, National University of Defense Technology, Changsha 410073, China.
Appl Opt. 2007 Dec 10;46(35):8446-52. doi: 10.1364/ao.46.008446.
The calculation model of fluorescence reabsorption and reemission with consideration of reflection on the boundary and material size using Monte Carlo method is proposed. To validate this stochastic model, experiments were conducted, and the calculated steady state spectra showed a good agreement with measurements. Using the absorption and fluorescence spectra of Yb-doped phosphate glass by careful measurements and corrections, we calculated the redshift in the observed fluorescence spectra and external quantum efficiency caused by fluorescence reabsorption and re-emission for the samples with the geometries of cylinder and cuboid. The calculation results show that the fluorescence reabsorption and re-emission have significant influence on the cooling efficiency. The calculation results also show that the cylinder with small waist beam incident (the incident light beam diameter is much less than the size of the sample, and goes through the center of the sample) is suitable for optical cooling.
提出了一种基于蒙特卡罗方法的考虑边界反射和材料尺寸的荧光重吸收和再发射计算模型。为验证该随机模型，进行了实验，计算得到的稳态光谱与测量结果吻合良好。通过仔细测量和校正，利用掺镱磷酸盐玻璃的吸收光谱和荧光光谱，计算了圆柱和长方体几何形状样品因荧光重吸收和再发射导致的观测荧光光谱红移和外量子效率。计算结果表明，荧光重吸收和再发射对冷却效率有显著影响。计算结果还表明，小腰束入射的圆柱体（入射光束直径远小于样品尺寸且穿过样品中心）适用于光冷却。
