群速失配对CsLiB6O10晶体谐波脉冲展宽的影响

对超短强激光脉冲在CsLiB6O10晶体中的群速失配进行了理论分析，采用傅里叶变换法推导超短脉冲二次谐波的耦合波方程。在Ⅰ类相位匹配下数值计算了脉冲宽度50fs的基波532nm，在CsLiB6O10晶体长度为0．5mm时产生二次谐波(266nm)的群速延迟量约100fs，并且随着晶体长度的增长，二次谐波的脉冲宽度几乎线性展宽。并得到了群速失配量△β1^（2）226．243fs／mm，低阶和二阶群速色散系数分别为β2^（3）=210．120fs^2／mm，β2^(3)=65．587fs^3／mm。其结果表明由于群速延迟和群速色散导致了谐波脉宽展宽和形变。

Pulse Expanded and Delaying Effect of Second Harmonic Wave in CsLiB6O10 by Group Velocity Mismatching and Dispersion

Group velocity mismatching and group velocity dispersion of fs laser pulse in CsLiB6O10 crystal are analyzed. The coupled equations of ultra-short pulse SHG are deduced by Fourier transform. The second harmonic pumped by 532 nm, 50 fs fundamental wave through CLBO is simulated numerically. The results show that the group velocity delay of second harmonic is about 100 fs at 266 nm through 0.5 mm lengths CsLiB6O10 and the second harmonic shape is widened linearly with the increase of crystal length. The group velocity mismatching Δβ(2)1=226.243 fs/mm, and lowness and second order group velocity dispersion β(2)2=210.120 fs2/mm, β(3)2=65.587 fs3/mm are reported for second harmonic on CsLiB6O10 crystal. The results indicate that group velocity mismatching and group velocity dispersion lead to the widening and defomation of the harmonic.