基于动量守恒和光参变过程中的三波耦合波方程, 和负单轴非线性光学晶体CsLiB6O10的色散方程, 研究了在光参变效应中超短激光脉冲由于群速度色散引起的展宽和形变。数值模拟显示, 在超短脉冲波形为双曲正割形和无啁啾调制时, 高阶群速度色散引起的超短脉冲为50 fs时, 晶体长度为10 mm, 紫外光213 nm作为基波入射时的脉冲展宽是波长为532 nm绿光在同等条件下的1.6倍。脉冲展宽程度与入射波长和晶体长度有关, 波长越短和晶体长度越长则脉冲展宽和波形变化越严重,高阶色散引起的超短高斯脉冲展宽, 将破坏其波形对称性并引起旁瓣现象。

The pulse expansion and deformation caused by group velocity dispersion in optical parametric effect of the negative uniaxial crystal CsLiB6O10 are studied, by momentum conservation and coupling wave equations. The numerical results show that, under the conditions of hyperbola secant wave form, no chirp modulation, pulse width of 50 fs and crystal length of 10 nm, the pulse expansion caused by group velocity dispersion for incident wavelength of 532 nm is 1.6 times of that for wavelength of 213 nm. The pulse expansion is related to the incident light wavelength and crystal length, and the pulse expansion and deformation are more severe for shorter wavelength and crystal length. The wave form symmetry is destroyed and the side band phenomena is also introduced by the pulse expansion.