拍瓦级激光系统前端波前热畸变和晶体动态热透镜效应的测量  

Wavefront measurement of crystal dynamic thermal lens effect and thermal abberations in a PW Ti:sapphire laser

作　　者：刘美标[1] 陆效明[1] 任志君[1] 梁晓燕[1] 

机构地区：[1]中国科学院上海光学精密机械研究所强场激光物理国家重点实验室．上海201800

出　　处：《红外与激光工程》2011年第5期835-839,共5页Infrared and Laser Engineering

基　　金：国家973计划(2006CB806000)

摘　　要：为了有效改善飞秒拍瓦激光系统的输出波前质量,研究了10Hz前端激光脉冲的波前随泵浦能量的变化特性。结果表明:由于增益介质的热效应,放大光束的斯特尔率(Strehl ratio)随泵浦能量的增加而下降,这说明光束的聚焦性能发生改变。利用波前展开的Zernike系数,进一步分析研究发现,由于热透镜效应,经多通放大的激光脉冲波前不仅离焦量发生了变化,像散量也发生了变化。离焦量和像散畸变是光束经过多程放大后畸变变化的两个主要分量,要改善波前必须予以补偿。在此基础上,用He-Ne光作为探测光,测量了实验装置中的钛宝石在不同泵浦能量下的热焦距,与基于钛宝石晶体参数计算出的理论值符合较好。In order to effectively correct the wavefront of the femtosecond petawatt laser pulses and improve the focus intensity,the wavefront abberation of the amplified laser beam of the front end of 10 Hz PW Ti：sapphire laser with different pump energies was measured.The results show that Strehl ratio of the amplified laser beam decreases with the increasement of the pump energy,so that the focus ability of the laser beam changes.Further analysis demonstrates that the defocus and the 0° astigmatism increase with pump energy increasement owing to the thermal lens effect.These two factors are the main abberations of laser beam out of the multi-pass amplifier which have to be actively compensated.Finally,a He-Ne laser beam was used as the probe to quantitatively measure the thermal focal length of the Ti：sapphire crystal pumped with different pulse energies,the results of which agreed well with the theoretical value based on the parameters of Ti：sapphire material.

关 键 词：波前测量 热透镜效应 飞秒激光 波前探测器 Zernike系数 

分 类 号：TN248.1[电子电信—物理电子学]