Effect of walk-off parameter, absorption-losses, and FCD on XPM-induced MI in SOI nanowaveguides

We numerically study the modulation instability (MI) due to cross-phase-modulation (XPM) at low input powers in a silicon-on-insulator (SOI) nanowaveguide. Generally, in the normal dispersion regime, the MI gain is obtained due to XPM. We have shown that the MI gain is possible due to free-carrier dispersion (FCD) interaction with nonlinearity when the walk-off parameter is zero. Further, we found that the FCD increases the gain and shifts the side lobes to a higher frequency when the walk-off parameter is non-zero.