Raman peak shifts due to walk-off in non-instantaneous Kerr media with higher-order effects
Michel-Rostand Soumo Tchio, Saïdou Abdoulkary, and Alidou Mohamadou
We study analytically and numerically the modulation instability (MI) of two incoherently co-propagating optical pulses in nonlinear fiber, taking into account high-order nonlinearity, walk-off effects, delay response time, and cross-phase modulation in several dispersion regimes. We show that higher-order nonlinearity is responsible for superposition of the secondary MI spectrum. We realize that there is a peak located in the emerged Raman band that we call “Raman peak” due to the combined effects of third-order dispersion, delay response time, and the opposite sign of the fourth-order dispersion parameter. These peaks are shifted toward higher frequencies when the walk-off increases.
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