神光II升级系统中束匀滑对三倍频的影响分析  

Analysis of Influence of Beam Smoothing on Third Harmonic Generation in SGII Upgrade

作　　者：季来林[1,2] 刘崇[1] 朱宝强[1] 邬融[1] 周申蕾[1] 林尊琪[1] 

机构地区：[1]中国科学院上海光学精密机械研究所,上海201800 [2]中国工程物理研究院上海激光等离子体研究所,上海201800

出　　处：《光学学报》2013年第12期214-219,共6页Acta Optica Sinica

摘　　要：基于非线性耦合波方程分析了神光II升级系统中束匀滑技术对三次谐波转换过程的影响。模拟结果显示:400μm焦斑所采用的连续相位板将引起1.4%左右的效率下降,近场对比度增加量约为0.02,均在可接受范围内;但当焦斑达到800μm时将会引起6%左右的效率下降,并导致近场对比度增加近0.05,无法兼容目前系统设计,必须进一步优化连续相位板设计方案;而谱色散匀滑技术引入光谱展宽达到60GHz时将引起5%左右的效率下降,且会引发明显的时间纹波扰动;但是谱色散匀滑引入的空间角谱扫描并不会明显影响谐波转换效率,因此在高通量运行时,需要适当减小调制带宽以提高谐波转换效率和系统的稳定性。The influence of beam smoothing on third harmonic generation （THG） in SGII upgrade is analyzed with the nonlinear coupled wave equation. Simulation results show that the continuous phase plate （CPP） designed for 400 μm focus spot causes the conversion efficiency decreasing by 1.4% or so, and the contrast of near field increasing by 0.02 or so in theory, which is within the acceptable tolerance. While the focus spot reaches 800 μm, the conversion efficiency decreases by about 6% and the contrast increases by 0.05 or so, which is out of the acceptable tolerance, and the scheme of the CPP should be improved. The 60 GHz bandwidth of smoothing by spectral dispersion （SSD） causes the conversion efficiency decreasing by about 5%, with obvious temporal intensity modulation, but influence of the divergence caused by SSD is very small. To maintain the stability of the THG, the bandwidth should be reduced reasonably at high fluence operation.

关 键 词：非线性光学 束匀滑 三次谐波转换 高功率激光 

分 类 号：O437.4[机械工程—光学工程] O780[理学—光学]