利用解析方法研究了父脉冲参数对合成脉冲宽度和质量的影响。研究结果表明,两个父脉冲具有相近的脉冲宽度和脉冲能量时,合成脉冲的时域质量较高。减小父脉冲时域宽度可以有效减小合成脉冲基底。为了验证这一相干脉冲合成的优化方法,在不同的非线性光纤中,对分束后的掺镱光纤飞秒激光器的输出脉冲分别进行非线性频率变换,获得了两个小于30 fs的脉冲,再将二者进行相干脉冲合成,获得了合成脉冲宽度为8 fs的少周期脉冲。

The effects of the parent pulse parameters on the width and quality of the synthesized pulse are investigated using an analytical method. The research results show that the time-domain quality of the synthesized pulse can be improved when the two parent pulses exhibit similar widths and energies, and the substrate of the synthesized pulse can be reduced by decreasing the time-domain widths of parent pulses. In order to verify the optimizing method for pulse coherent synthesis, the pulse output obtained from the Yb ³⁺-doped fiber femtosecond laser system is first divided into two branches, then they are treated by nonlinear frequency conversion in different nonlinear fibers, respectively, and finally two pulses with pulse durations of less than 30 fs are obtained. These two pulses are further coherently synthesized. Consequently, after coherent synthesis, a few-cycle laser pulse with a pulse duration of 8 fs is realized.