BBOⅠ类相位匹配光参量放大中群速失配的补偿

描述了在BBOⅠ类相位匹配的飞秒光参量放大（OPA）中，利用非共线结构和倾斜抽运光的脉 冲波面来完全补偿三波群速失配的方法.理论计算了三波群速匹配时，非共线角、相位匹配 角、抽运光的脉冲波面倾斜角随信号光波长的变化，并分析了对抽运光光斑尺寸的要求和对 空间走离长度的影响.结果表明，利用该方法不仅能够实现最大的参量带宽，而且能够完全 补偿飞秒OPA中三波的群速失配.此外，选取合适的抽运光光斑尺寸和非线性晶体的长度对提 高参量增益也至关重要. 关键词： 群速匹配 非共线相位匹配 脉冲波面倾斜 飞秒光参量放大

Compensation of group velocity mismatch for optical parametric amplification in BBO type-I phase-matched configuration

A method that compensates completely the group velocity mismatch between three w aves for femtosecond optical parametric amplification (OPA) in BBO type-I phase- matched configuration is presented by combining noncollinear configuration with tilting pump wave front. When the group velocities of the three waves are matche d, the variations of the noncollinear angle, the phase-matched angle and the pum p wave front tilt angle with the signal wavelength are calculated theoretically, and the effects of the pump beam size and the spatial walk-off length are analy zed. The results indicate that this method not only can achieve maximal parametr ic bandwidth, but also can match completely the group velocities between three w aves for femtosecond OPA. In addition, with increasing parametric gain, it is ve ry importance to appropriately choose the pump beam size and the nonlinear cryst al length.