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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。
The chirped pulse amplification (CPA) system based on Yb3 + doped fiber was experimentally studied. The semiconductor saturable absorber mode-locked fiber laser is used as the seed source, and the pulse with the wavelength of 1030 nm is broadened to hundreds of picoseconds by chirped pulse amplification. A multi-stage Yb-doped single-mode optical fiber and double-clad fiber are used to form a preamplifier. The main amplifier adopts a Yb-doped rod-like photonic crystal fiber with a large mode field as a laser working substance, achieving a repetition frequency of 211 k Hz and a power of 50 W Single-mode picosecond pulse output. By controlling the gain and the non-linear accumulation of each fiber amplifier in the amplification system, the influence of the nonlinear effect on the time-domain characteristics of the pulse is effectively suppressed. The output of the amplified pulse is compressed by a reflective grating pair, and the laser output with a pulse width of 887 fs is finally obtained. The energy per pulse reaches 124 μJ and the peak power is 139.8 MW. The experimental results are the first reported in China based on fiber structure 100 micro-focus femtosecond laser system.