Song Huanyu, Liu Bowen, Chen Wei, Li Yuan, Song Youjian, Wang Sijia, Chai Lu, Wang Chingyue, Hu Minglie
Opt Express. 2018 Oct 1;26(20):26411-26421. doi: 10.1364/OE.26.026411.
Compressing picosecond laser pulses to the femtosecond level is an attractive shortcut for obtaining femtosecond laser pulses. However, dechirped pulses generated by nonlinear compression with self-phase modulation (SPM) show obvious pedestals, which are induced by nonlinear chirp accumulation in spectral broadening process and cannot be easily suppressed. Here, we report systematic numerical simulations and experimental studies on self-similar amplification of picosecond pulses in a short gain fiber for obtaining ~100-fs laser pulses with nearly transform-limited (TL) temporal quality. It is demonstrated that self-similar amplification with picosecond seed pulses is only sensitive to pulse duration and pulse energy. Based on this optimization guideline, we built a compact self-similar amplification fiber system with a picosecond fiber laser as the seed source. This system outputs 66-fs pulses with 6.1-W average power at a repetition rate of 30 MHz. Due to the linear chirp produced in self-similar evolution process, compressed pulses show nearly TL temporal quality. It promises an efficient way of obtaining high-quality femtosecond laser pulses from a picosecond laser source.
将皮秒激光脉冲压缩至飞秒量级是获得飞秒激光脉冲的一种颇具吸引力的捷径。然而，通过自相位调制（SPM）进行非线性压缩产生的去啁啾脉冲会出现明显的基座，这是由光谱展宽过程中的非线性啁啾积累引起的，且不易被抑制。在此，我们报告了关于在短增益光纤中对皮秒脉冲进行自相似放大以获得具有近变换极限（TL）时间质量的~100飞秒激光脉冲的系统数值模拟和实验研究。结果表明，皮秒种子脉冲的自相似放大仅对脉冲持续时间和脉冲能量敏感。基于此优化准则，我们构建了一个以皮秒光纤激光器作为种子源的紧凑型自相似放大光纤系统。该系统在30 MHz的重复频率下输出平均功率为6.1 W的66飞秒脉冲。由于在自相似演化过程中产生的线性啁啾，压缩后的脉冲具有近乎TL的时间质量。这为从皮秒激光源获得高质量飞秒激光脉冲提供了一种有效方法。
