随机性对部分随机介质激光器阈值的影响

基于速率方程和Maxwell方程相结合的模型，采用时域有限差分法(FDTD)研究了介质的随机性和层数对部分随机介质激光器阈值的影响.模拟结果显示，当抽运速率超过阈值时，出现一个或者多个振荡模；随机性或者系统的尺度增加时，振荡模数量也增加；部分随机介质激光器的阈值在一定的随机强度和层数下将达到最小值，它与完全随机情况下的结论有所不同.对所得到的结论给出了物理解释.这些结果对于制作随机激光器和光集成潜在应用价值. 关键词： 激光物理 随机激光器 阈值 时域有限差分法

Effect of the strength of randomness on lasing threshold in one-dimensional partially random media

Based on the model of the Maxwell's equations coupled with the rate equations of electronic population, the lasing threshold of optical modes in partially random media is analyzed using the finite difference time domain method. The characteristics of random laser can be described by some factors, such as the strength of randomness, size of medium,etc.,which determine the lasing threshold in random medium. The simulated results show that one or more lasing modes appear when the pumping rate P_r increases beyond the threshold, and the number of modes will increase with random strength and size of medium. In addition, the simulated results demonstrate that the lasing threshold value will attain the minimum value under certain random strength and size of medium, which is at variance with the theoretical result in one-dimensional completely random medium. Such properties of the medium show potential advantage in future application for optical integration.