发散光束小尺度自聚焦特性的研究  

Small-Scale Self-Focusing of Divergent Beams

作　　者：顾亚龙[1] 朱健强[1] 

机构地区：[1]中国科学院上海光学精密机械研究所高功率激光物理国家实验室

出　　处：《光学学报》2006年第11期1734-1738,共5页Acta Optica Sinica

摘　　要：研究了发散光束的小尺度自聚焦效应。从非线性傍轴波动方程出发,利用坐标变换,推导出发散光束小尺度扰动的传输方程,进而得到小尺度扰动增长的临界频率、最大增长频率和相应B积分值的变化规律。研究了发散光束初始曲率半径对小尺度自聚焦效应的影响。结果表明,对于一定的传输距离,随着发散光束初始曲率半径的减小,小尺度扰动的最大增长频率减小,相应的最大增益减小,即B积分值也减小。对于一定的初始曲率半径,随着传输距离的增大,B积分值增长变缓,并最终停止。利用局部能量守恒定律研究了发散光束的成丝距离,发现小的初始曲率半径可以延长成丝距离。The small-scale self-focusing of divergent beams is studied. Based on the nonlinear paraxial wave equation, the propagation equation of small-scale perturbation of divergent beams has been deduced with a coordinate transformation. The evolvement law of the growth critical frequency of small-scale perturbation, maximum growth frequency and relative B integral is obtained. The influence of the initial radius of divergent beams on small-scale self-focusing is discussed. It is found that for a given propagation distance, the fastest growing frequency, the maximum perturbation growth, and thus the B integral decrease with the decrease of the initial radius of divergent beams. For a given initial radius, as the propagation distance increases, the growth of the B-integral becomes slow and stops at last. Also, the expression for the distance at which the filaments are formed is obtained by local energy conservation, and it is shown that a small initial radius extends the filamentation distance.

关 键 词：非线性光学 小尺度自聚焦 成丝 B积分 

分 类 号：O437.5[机械工程—光学工程]