激光等离子体对光束阻断效应的研究

Effect of beam of light blocked by laser plasma

实验中利用锁模 Nd:YAG 激光(脉冲串时间长度59.2 ns,单脉冲宽度20.69 ns)经透镜聚焦于大气中,诱导大气发生光学击穿,在不同的入射光强下,对经过光致等离子体的透射光与入射光的时间波形进行了测量。测量结果表明:入射光束经过光致等离子体时受到强烈吸收,从而表现出光致等离子体对入射光束的阻断效应。还发现入射光越强,光致等离子体区域内部电子的扩散损耗相对越小,入射光受光致等离子体阻断的效果越明显。当锁模 Nd:YAG 激光连续两次通过等离子体区域,随着光束通过等离子体长度的增加,光束受阻程度变得更加严重。

Laser-induced air breakdown has arisen when Nd^(3+):YAG laser is focused in the air,using a Nd^(3+): YAG laser with 59.2 ns pulsed train length and 20.69 ns single pulse width.The time graph of incident laser and transmitting laser passing plasma is measured in different laser intensity.Following result are Obtained,because laser is absorbed intensively while passing laser plasma,there is blockade effect of incident laser is.The smaller electron diffusion in the plasma is,the more distinct blockade effect of incident laser is.When Nd^(3+):YAG laser passing plasma twice in the part of experiment,with the length of laser plasma increasing,the blockade effect of incident laser becomes more serious.