正常色散平坦光纤中皮秒抽运脉冲超连续谱的形成研究

Investigation of supercontinuum generation in normal dispersion-flattened fiber by picosecond seed pulses

研究了皮秒抽运脉冲在正常色散平坦光纤中超连续谱的形成过程,分析了脉冲演化过程中光波分裂的产生及其所显示的四波混频对超连续谱特性的影响.结果表明:脉冲初期光谱展宽由自相位调制效应主导,此后由于光谱中心区域能量在色散作用下不断向旁瓣转移,自相位调制效应逐渐减弱而四波混频作用增强,光谱会再度显著展宽.超连续谱的噪声特性与光谱演化状态密切相关,是光谱特征结构对抽运脉冲强度噪声响应的动态表征.

The evolution of picosecond seed pulses in the normal dispersion-flattened fiber to generate supercontinuum （SC） is investigated. The appearance of wave breaking during the process and the effect of the revealed four-wave mixing on the characteristics of SC are also analyzed. The research indicates that the broadening of the pulse spectrum in the initial stage is dominated by the self-phase modulation. Afterwards, self-phase modulation is impaired while four-wave mixing is enhanced due to energy in the inner spectrum region being transferred continuously to the outside wings by dispersion, and the pulse spectrum further broadens remarkably. The characteristic of SC noise manifests the dynamic responses of typical SC spectral structures to the seed pulse amplitude noise that are closely related to the evolution.