用钛宝石再生放大器产生高重复率啁啾脉冲列

针对啁啾脉冲放大技术建成的钛宝石激光装置，提出一种获得高重复率激光脉冲列的方法.通过改变钛宝石再生放大器中泡克耳斯盒电光开关的传统工作模式，使得腔内放大的脉冲从某特定时刻起，每当在腔内往返一次就以一定的倒出比例（倒出率）倒出腔内脉冲能量的一部分，从而可以在有限的时间段内产生高重复率的啁啾激光脉冲列.基于Franz-Nodvik放大理论，建立了该高重复率再生放大器的理论模型，通过数值计算，系统地分析了初始增益、倒出时刻、倒出率对输出的脉冲序列的影响.在抽运功率为35mJ、倒出率为1/2的实验条件下，通过腔外的脉冲数量选择器，在一个抽运周期内的有限时间段内已获得了14个幅度相近、单脉冲能量约为0.02mJ、重复率为100MHz的啁啾脉冲序列.从此啁啾脉冲列中选取数个脉冲，通过10TW级的激光系统放大和压缩，已获得100MHz重复率的飞秒太瓦级脉冲列. 关键词： 高重复率 多通放大 啁啾脉冲放大 钛宝石激光器

Generation of chirped pulses at high repetition rate with a Ti:sapphire regenerative amplifier

We present a method to obtain a laser pulse train at high repetition rate for the Ti:sapphire laser system based on the chirped pulse amplification technique.The conventional working mode of the Pockels cell in the Ti:regenerative amplifier is modified.At a certain dumping time,a portion of the amplified seed pulse is dumped out of the cavity by a certain dumping ration every time the pulse runs around the cavity.Thenceforward,the chirped pulses at high repetition rate are generated.Based on the Franz-Nodvik amplification theory,a theoretical model of the regenerative amplifier is established and the analysis of the dependence of the pulse sequence on the dumping time and dumping ratio is given by numerical computation.With a pumping energy of 35mJ and a dumping ratio of 1/2,a fourteen-pulse sequence at 100MHz with pulse energy of 0.02mJ is obtained at a finite period of time in a pumping cycle.