中文摘要：

从啁啾脉冲放大的基本理论出发,详细计算了啁啾脉冲在多通预放大中各个时间点的增益情况,并设计了一个十通预放大器进行了实验研究.结果显示,在抽运通量为1.6J/cm2的非饱和放大情况下,种子脉冲经过十通预放大之后信噪比由10-5提高到10-7.这表明在非饱和抽运通量下,多通预放大器可以有效提高激光脉冲的信噪比.

英文摘要：

According to the theory of chirped pulse amplification （CPA）,we analyze numerically the gain characteristic of laser pulses in multi-pass amplifier.A CPA Ti：sapphire laser with 10-pass scheme is designed and built.The experimental result shows that the contrast ratio of the femtosecond pulse is obviously enhanced by two orders from 10-5 to 10-7 under a pump flux of 1.6 J/cm2.This work demonstrates that the contrast ratio of the amplified femtosecond laser pulse could be effectively improved by multi-pass preamplifier.