突发运行模式下的飞秒碟片再生放大器

Femtosecond Thin-Disk Regenerative Amplifier Under Burst Operation Mode

为了获得高重复频率的飞秒激光脉冲,将突发运行模式引入飞秒碟片再生放大系统中。通过将再生放大器的腔长设计为9.3m,激光系统输出了接近衍射极限的激光脉冲,且激光脉冲的重复频率为电光调制频率的5倍。在电光调制频率为5kHz、吸收的抽运功率为98 W的条件下,获得了最高输出功率为10.7 W、光谱半峰全宽为1.18nm、脉冲宽度为777fs的双曲正割脉冲输出。再生放大器的光-光转换效率随着电光调制频率的增加而增加,从频率为0.5kHz时的12.4%增加到频率为5kHz时的25.3%。激光的输出稳定性在18~20℃的温度区间内随着水冷温度的降低而提高,激光系统输出功率的均方根从20℃时的0.93%变为18℃时的0.52%。该研究结果对于设计具有高重复频率、高功率且性能稳定的飞秒激光系统具有参考价值。

In order to obtain femtosecond laser pulses with high repetition rate, a burst operation mode is introduced into femtosecond thin-disk regenerative amplification system. The cavity length of the regenerative amplifier is designed as 9.3 m, so that the laser pulse which is close to the diffraction limit can be generated. The repetition rate of the laser pulse is 5 times of the electro-optic modulation frequency. Under the condition that the electro-optic modulation frequency is 5 kHz and the absorbed pump power is 98 W, hyperbolic secant pulses with maximum output power of 10.7 W, spectrum full-width-half-maximum （FWHM） of 1.18 nm, pulse width of 777 fs are obtained. The optical-optical conversion efficiency of the regenerative amplifier increases with the increasing of the electro-optic modulation frequency, and the optical-optical conversion efficiency increases from 12.4% at 0.5 kHz to 25.3% at 5 kHz. The laser output stability improves in the range of 18-20 ℃ with the decreasing of chiller temperature, and the output power root-mean-square of the laser system changes from 0.93% at 20 ℃ to 0.52% at 18 ℃. These results have great values for designing the stable femtosecond laser system with high repetition rate and high power.