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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30μm,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7μm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15μm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 three-stage main oscillator power amplifier (MOPA) architecture was used to establish a picosecond pulse ytterbium-doped fiber laser with an average output power of 30 W. The output core diameter is 30μm, the output laser pulse width is about 20 ps, the repetition frequency is 59.8 MHz and the beam quality factor M2 is less than 1.5. The high-power pulsed laser was coupled to a domestic photonic crystal fiber (PCF) with a core diameter of 7 μm to achieve a near 3 W supercontinuum output. In order to increase the coupling efficiency and avoid the optical fiber end face damage, a supercontinuum with a core diameter of 15μm was added between the picosecond laser source and the photonic crystal fiber. The output supercontinuum has a good flatness. The -10 dB spectral width exceeds 1100 nm, with the exception of the remaining laser peak at 1064 nm, which is beyond the observation range of 600 to 1700 nm for the spectrometer used. The output light spot is a white base-mode spot with a hexagonal color envelope.