数值计算了LBO晶体中基频光波长为1064 nm时，在I类倍频相位匹配范围内所有匹配方向上慢、快光的走离角、互作用角和折射率。基频慢光的走离角范围为0°~1.35°，倍频快光的走离角范围为0°~1.52°，慢快光互作用角范围为0°~1.15°；在不忽略三波走离角、互作用角以及折射率的变化的情况下，数值求解了三波耦合波方程及在各相位匹配方向上倍频转化效率随通光长度的变化规律。结果表明,在匹配方向约为(42.2°，19°)时转化效率达到极大值，约为3.35%。在每一匹配角方向上，其转化效率与通光长度的平方成正比。

The walk-off angle, interaction angle and refractive index are calculated with numerical methods under type I frequency-doubling phase-matching direction, while the fundamental frequency wavelength is 1064 nm in LBO crystal. The walk-off angle of the fundamental frequency wavelength is 0°~1.35°. The walk-off angle of the doubling frequency wavelength is 0°~1.52°. The interaction angle between fundamental frequency and doubling frequency waves is 0°~1.15°. The coupled wave equations and the conversion efficiency are numerical calculated considering the change of walk-off angle, the interaction angle and the refractive index. The results show that the conversion efficiency has maximum value (3.35%) when the phase matching direction is about (42.2°, 19°). In addition, the conversion efficiency is proportional to the square of the crystal length.