蒙特卡罗法计算无序激光器的阈值

提出了计算无序激光器阈值增益的模型，提出了已知平均自由程和散射强度分布得到分布函数及相应的随机变量的方法.对各向同性的光散射，导出了各分布函数，并在每次散射中得到相应的随机变量.运用蒙特卡罗法模拟光子在无序介质中的随机行走，得到了无序激光器的阈值.讨论了阈值增益与光子平均自由程、增益区半径、增益区深度、非增益区光吸收系数的关系，提出了降低阈值的方法.理论结果与实验数据是符合的.关键词：激光物理阈值蒙特卡罗散射

Calculating the threshold of random laser by using Monte Carlo method

We put forward a model of calculating the threshold gain of random laser, a method for obtaining the distribution function and the relevant random variables according to the mean free path and scattering intensity distribution. The distribution functions are derived for isotropic scattering of light, and then we get the random variables according with the distribution at every scattering. Simulating the random walk of photons in random media by using Monte Carlo method, the threshold of random laser is got. The relationship of the threshold gain to the photon mean free path, the radius of gain zone, the depth of gain zone and light absorption coefficient of non-gain zone is discussed. We make some suggestions to lower the threshold. The theoretical results agree with the experimental data.