The effects of fourth-order dispersion (FOD) on modulation instabilities in the twin-core optical fibers with the asymmetric CW state are studied systematically. When the product of the group velocity dispersion and FOD is negative, in the anomalous dispersion regime, two new MI bands in the high frequency are generated with one band either having the equivalent gain with that of original band or dominating the MI depending on the FOD value; in the normal dispersion, a new dominant MI band in the high frequency is always generated, and the original MI bands vanish in the presence of FOD at total power above a critical value. When the product of the group velocity dispersion and FOD is positive, the main effect of FOD is to shift the MI band to the low frequency and reduce the bandwidth simultaneously with minor effects on the instability gain. We also find that the effects of linear coupling coefficient dispersion can be significantly suppressed in the presence of FOD especially...

中文翻译：

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四阶色散对不对称CW态双芯光纤调制不稳定性的影响

系统研究了四阶色散（FOD）对CW不对称双芯光纤调制不稳定性的影响。当组速度色散和FOD的乘积为负时，在异常色散状态下，会生成两个高频的新MI频带，其中一个频带的增益与原始频带相同，或者取决于FOD占主导地位值; 在正常色散下，总是会在高频中产生一个新的主导MI频带，并且当FOD存在且总功率高于临界值时，原始MI频带将消失。当群速度色散与FOD的乘积为正时，FOD的主要作用是将MI频带移至低频并同时减小带宽，而对不稳定性增益的影响较小。