以一定重复频率工作的KTP倍频效率的演化规律

The evolution law of KTP SHG conversion efficiency in special repetition rate

基于导带电子密度和材料的有效介电函数的表达式,推导了KTP晶体对532nm光波的吸收系数.对比研究了不同峰值功率密度和重复频率下KTP晶体的导带电子密度和532nm吸收系数的演化规律,以及倍频转换效率的演化规律.结果表明,随着导带电子密度的增加,KTP晶体532nm吸收系数随之增加,其倍频转换效率随之减小;当基频光入射功率密度一定时,不同重复频率脉冲作用引起的导带电子密度存在积累效应,导致KTP晶体532nm透过率及倍频转换效率均随着作用时间的增加呈指数形式变化,随着脉冲重复频率的增加其积累效果更加明显,但随着作用时间的增加,导带电子密度、吸收系数均趋于同一稳定值.

Based on the conduction band electron density and the expression of the effective dielectric function,the absorption coefficient at 532nm of KTP crystal is deduced. The evolution law of conduction band electron density,absorption coefficient and second harmonic generation （ SHG） conversion efficiency are comparatively studied. The results are as follows. The 532 nm absorption coefficient of KTP crystal is increasing with conduction band electron density,and the SHG conversion efficiency is decreasing with conduction band electron density. When the power density of fundamental frequency laser is a fixed value,conduction band electron density shows accumulation effects a different repetition rates, which caused the 532 nm transmission and the SHG conversion efficiency of KTP crystal to vary exponentially with acting time,and the accumulation effect is increasing obviously with repetition rate,but conduction band electron density and absorption coefficient approach thir steady values.