论文部分内容阅读
通过理论分析与数值模拟方法,研究了高功率激光系统中非线性热像位置及光强随介质厚度的变化规律。基于角谱传输和Bespalov-Talanov小尺度自聚焦理论,在不作薄介质近似情况下得到了热像光强表达式,并用数值模拟结果进行了验证。结果表明,在一定的入射功率下,热像光强随介质厚度的增加而增大;而在一定的B积分下,热像光强随介质厚度的增加先单调增加,达到一极大值后,单调减小。此外,当模糊斑相对于克尔介质的距离的菲涅耳数远大于1时,可采用薄介质近似。数值模拟结果与解析结果吻合得很好。
Through theoretical analysis and numerical simulation, the variation of nonlinear thermal image position and light intensity with the thickness of medium in high power laser system is studied. Based on the angular spectrum transmission and Bespalov-Talanov small-scale self-focusing theory, the thermal imaging intensity expression is obtained without thin medium approximation and verified by numerical simulation. The results show that at a given incident power, the intensity of thermal image increases with the increase of the thickness of the medium. Under a certain B-integral, the intensity of thermal image increases monotonically with the increase of the thickness of the medium. After reaching a maximum, , Monotonically reduced. In addition, the thin medium approximation can be used when the Fresnel number of the blur spot relative to the Kerr medium is much greater than 1. The numerical simulation results agree well with the analytical results.