采用三级主振荡功率放大(MOPA)结构,建立了一台平均输出功率30 W的皮秒脉冲掺镱光纤激光器。其输出尾纤芯径为30 μm,输出激光脉宽约20 ps,重复频率为59.8 MHz,光束质量因子M2小于1.5。将该高功率脉冲激光耦合到芯径7 μm的国产光子晶体光纤(PCF)中,实现了近3 W的超连续谱输出。为了增加耦合效率并避免光纤端面损伤,在皮秒激光源与光子晶体光纤之间加上一段芯径15 μm的过渡光纤,得到的输出超连续谱具有很好的平坦性。-10 dB谱宽超过1100 nm(其中1064 nm处残留的激光峰除外),超出所用光谱仪600-1700 nm的观测范围。输出光斑为一带有六角形彩色包络的白色基模光斑。

A picosecond ytterbium-doped fiber laser with average power of 30 W is constructed with a tri-stage master oscillator power amplifier (MOPA) configuration. The laser exhibits a pulse width of 20 ps,repetition rate of 59.8 MHz,and a beam quality M2 of less than 1.5. The diameter of the output fiber core is 30 μm. By using the laser as a pump source,near 3 W supercontinuum is generated from a section of homemade photonic crystal fiber (PCF) with 7 μm core diameter. An extra section of fiber with 15 μm core diameteris arranged between the picosecond laser source and the PCF so as to increase the coupling efficiency and avoid fiber facet damage. The supercontinuum covers the whole spectral range from 600 to 1700 nm of the optical spectrum analyzer. The unflatness of the spectrum is less than 10 dB (except for the residual pump laser peak at 1064 nm). The output beam spot is a white fundamental mode with a chromatic hexagonal surrounding.