飞秒激光脉冲倍频的实验研究

Experimental Study on Frequency Doubling of Femtosecond Pulses

利用2mmKDP晶体对中心波长790nm、脉冲宽度75fs、晶体表面强度约1011W/cm2的超短超强激光脉冲进行了倍频实验研究。通过对基频脉冲能量及频率啁啾的优化,可以获得高于40%的能量转化效率。观测了基频脉冲频率啁啾对倍频光产生的影响,发现激光脉冲啁啾为零时对应的倍频转化效率最高;对于相同的光栅相对位置,正啁啾基频脉冲的倍频转化效率高于负啁啾。

This paper studies the frequency doubling of femtosecond laser pulses with a wavelength of 790 nm using a 2 mm thick KDP crystal. The energy conversion efficiency is better than 40% after the energy and chirp of the fundamental harmonic are optimized. Moreover, the frequency doubling is analyzed as a function of laser pulse frequency chirp. It is found that the frequency doubling conversion efficiency reaches a maximum when there is no frequency chirp; for the same grating position, the frequency conversion efficiency is better by using positively chirped fundamental laser pulses than by using negatively chirped pulses.