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本文利用非线性偏振锁模激光器产生的重复频率50MHz,脉宽为1.8ps的脉冲分别抽运外径均匀和色散渐减两种高非线性光子晶体光纤,在三阶非线性效应(自相位调制、交叉相位调制、四波混频和受激拉曼散效应等)和色散共同作用下得到扩展至蓝光部分的超连续谱.模拟了光谱在色散渐减光纤和均匀光纤中的展宽过程,通过对比均匀光纤发现色散渐减光纤在调控色散,加强拉曼孤子和色散波的群速度匹配条件,产生超带宽光谱方面具有很大优势.实验利用20m长的色散渐减光纤,得到了406.1至671.8nm的可见光波段增强的较为平坦的超连续谱.
In this paper, two highly nonlinear photonic crystal fibers with uniform outer diameter and decreasing dispersion are respectively pumped by pulses generated by a nonlinear polarization mode-locked laser with a repetition rate of 50MHz and a pulse width of 1.8ps. In the third-order nonlinearity (self-phase modulation , Cross-phase modulation, four-wave mixing and stimulated Raman scattering, etc.) and dispersion are combined to obtain a supercontinuum extending to the blue light. The broadening of the spectrum in the destructive and uniform fibers is simulated by Compared with the uniform fiber, it is found that the fiber with decreasing dispersion has great advantages in controlling the dispersion, strengthening the group velocity matching condition of Raman soliton and the dispersion wave, and producing the ultra-wideband spectrum. By using 20m long dispersion decreasing fiber, the optical fiber 406.1 to 671.8 nm in the visible band enhancement of the relatively flat supercontinuum.