百微焦级飞秒光纤激光放大系统

Hundred Micro-Joules Level Femtosecond Fiber Laser Amplification System

实验研究了基于掺Yb3+光纤的啁啾脉冲放大(CPA)系统。利用半导体可饱和吸收体锁模光纤激光器作为种子源,采用啁啾脉冲放大技术,将波长为1030 nm的脉冲展宽到数百皮秒进行放大。采用多级的掺镱单模光纤和双包层光纤组成预放大器,主放大器采用大模场的掺镱棒状光子晶体光纤作为激光工作物质,实现了重复频率为211 k Hz,功率为50 W的单模皮秒脉冲输出。通过合理地控制放大系统中每一级光纤放大器的增益以及非线性积累量,有效抑制了高能脉冲放大过程中非线性效应对脉冲时域特性的影响。采用反射式光栅对,对输出的放大脉冲进行压缩,最终获得了脉宽为887 fs的激光输出,单脉冲能量达到124μJ,对应峰值功率为139.8 MW,该实验结果为国内首次报道基于光纤结构的百微焦级飞秒激光系统。

A fiber chirped pulse amplification system based on Yb8. doped fibers is demonstrated. The seeder is a mode-locked fiber laser with semiconductor saturable absorber, the chirped pulse amplification technique is applied to stretch the 1030 nm pulse to several hundred picoseconds to be amplified, The single mode picosecond pulses with average power of 50 W and repetition rates of 211 kHz are achieved by using multistage pre-amplifier consisted with Yb~＊ doped single mode fiber amplifier and double cladding fiber amplifier and the main amplifier with a large mode area rod-typed photonic crystal fiber as the laser gain material. Properly controlled the gain and the nonlinearity in every step of the amplification system, the influence of nonlinear effects are effectively suppressed on the pulse of time domain in high energy amplification. Laser pulses with pulse duration of 887 fs are generated by a reflective grating-pair compressor, corresponding to single pulse energy of 124 μJ and peak power of 139.8 MW. This experimental result of hundred micro joules level femtosecond laser based on fiber structure is firstly reported in China.