三阶色散对拉曼频移的增强和抑制作用

Enhancement and Suppression of Raman-Induced Frequency Shifts by Third-Order Dispersion in Photonic Crystal Fibers

基于光子晶体光纤(PCF)中脉冲演变遵循的非线性演化方程,用数值方法研究了三阶色散(TOD)对孤子拉曼自频移(RIFS)的影响。结果表明,在反常色散区,正的三阶色散对孤子拉曼自频移有抑制作用,而负的三阶色散却对频移有增强作用。当输入脉冲较窄,色散波产生的距离较短时,由于频谱反弹效应,三阶色散对频移增强的作用在光纤的零色散波长处会被抑制。输入脉冲的峰值功率和形状对拉曼频移被抑制所需光纤的长度有重要的影响。在正常色散区,三阶色散对拉曼频移的影响可忽略不计。

By numerically solving the extended nonlinear Schrodinger equation, it is shown that Raman-induced self- frequency shift （RIFS） can be manipulated by third-order dispersion （TOD） in photonic crystal fibers （PCFs）. In the anomalous dispersion regime, RIFS can be decreased by the positive TOD and enhanced by the negative TOD, respectively. The enhancement of RIFS by negative TOD can be suppressed by the spectral recoil effect. The variation of peak intensity and profile of input pulse plays an important role on RIFS. In the normal dispersion region, the influence of TOD on RIFS is nonsignificant due to the rapid temporal spreading.