Abstract
We analyze the modulational instability (MI) of a continuous wave (CW) in saturable fiber systems, including higher-order dispersions, self steepening, and self-frequency shift, cubic, quintic, and septic nonlinearities. We show that whenever the combined effect of higher-order dispersion and non-Kerr nonlinearities with suitable systems meets a wide variety of MI behaviors by mixing different combinations are presented. By modifying the nonlinear Schrödinger equation (NLSE) for MI analysis using Maxwell's theory, the new solution is derived for linear stability analysis to obtain an expression for the MI gain. Among different combinations of higher-order dispersion and non-Kerr nonlinearities, the critical behavior of MI gain suppressed under saturable systems, which leads to affect the nature of soliton stability. Under the activation of self steepening and self-frequency shift in the saturable system, the generated MI behavior regained its original to retain the soliton stability. This kind of new and tuning of MI behavior will be a useful instrument in nonlinear optic communications with straightforward applications.