Cao Huabao, Lu Xingqiang, Li Linbo, Yin Xianhua, Ma Weixin, Zhu Jian, Fan Dianyuan
Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
Appl Opt. 2011 Jul 10;50(20):3609-14. doi: 10.1364/AO.50.003609.
FM-to-AM conversion in the ninth beam of the Shen Guang II laser system with sinusoidal phase-modulated spectra is calculated and analyzed. The simulations show that the intensity modulation at 3ω is much more serious compared to the other wavebands and it is mostly induced by the frequency conversion system rather than the amplification chain. The compensation effects of FM-to-AM conversion in the frequency conversion system by angular dispersion grating and cascaded crystals are numerically simulated and compared. Compared to the cascaded crystals, the angular dispersion grating could maintain higher frequency conversion efficiency with wide spectral width and offer a higher dynamic range of compensation effectiveness versus fundamental laser intensity. Combined with a precompensation filter before the amplification chain, FM-to-AM conversion at 3ω could be eliminated.
对神光Ⅱ激光系统第九束光中具有正弦相位调制光谱的调频到调幅转换进行了计算与分析。模拟结果表明，与其他波段相比，三倍频处的强度调制更为严重，且主要由频率转换系统而非放大链引起。对角度色散光栅和级联晶体在频率转换系统中对调频到调幅转换的补偿效果进行了数值模拟与比较。与级联晶体相比，角度色散光栅能在较宽光谱宽度下保持较高的频率转换效率，且在补偿效果相对于基频激光强度方面具有更高的动态范围。结合放大链前的预补偿滤波器，可消除三倍频处的调频到调幅转换。
