实验研究了高重复频率、宽光谱皮秒脉冲掺镱光纤激光器。该激光器为全光纤结构，采用主控振荡器的功率放大器技术，利用光纤中的非线性效应进行光谱的展宽。利用半导体可饱和吸收镜实现振荡器的被动锁模,输出中心波长为1031.3 nm，3 dB光谱宽度为1.51 nm，脉冲宽度为3.1 ps，重复频率为21.3269 MHz。再利用声光调制器使振荡器的重复频率降低到2.1 MHz，降频后的信号光通过三级掺镱光纤放大器，在30 μm/250 μm大模场双包层掺镱光纤中实现了功率主放大，最后得到平均功率为20 W、脉冲宽度为20.8 ps、光谱宽度为640~1700 nm、单脉冲能量为9.5 μJ、对应峰值功率为0.46 MW的脉冲激光输出。

A high repetition rate and wide spectrum picosecond pulsed all-fiber Yb-doped laser is experimentally studied. The laser with all-fiber structure uses the master oscillator power amplifier technology. The broadening of the spectrum is caused by the nonlinear effect. Passively mode-locked technique of oscillator is realized by semiconductor saturable absorber mirror. The laser operates at 1031.3 nm with 3 dB spectral width of 1.51 nm. Its pulse width is 3.1 ps and the repetition frequency is 21.3269 MHz. An acoustic-optic modulator is applied to reduce the repetition rate to 2.1 MHz. The down-converted signal light passes through a three-stage Yb-doped fiber amplifier, and the main power amplification is realized in 30 μm/250 μm large mode field double-clad Yb-doped fiber. In the end, the pulse laser output is obtained with average output power of 20 W, pulse width of 20.8 ps, spectrum range from 640~1700 nm, single pulse energy of 9.5 μJ, and corresponding peak power of 0.46 MW.