A colloquium on the influence of versatile class of saturable nonlinear responses in the instability induced supercontinuum generation

•We investigate the modulational instability induced supercontinuum generation under versatile saturable nonlinear responses.•The significance of the functional form of satuable nonlinearity in the generation of supercontinuum is analyzed.•The exponential saturable nonlinearity is identified to achieve broadest spectrum than the rest.•A novel active regime is found in the instability spectrum of saturable nonlinearity.•The quality of supercontinuum is studied through coherence analysis.

We investigate the modulational instability induced supercontinuum generation (MI-SCG) under versatile saturable nonlinear (SNL) responses. We identify and discuss the salient features of saturable nonlinear responses of various functional forms such as exponential, conventional and coupled type on modulational instability (MI) and the subsequent supercontinuum (SC) process. Firstly, we analyze the impact of SNL on the MI spectrum and found both analytically and numerically that MI gain and bandwidth is maximum for exponential nonlinearity in comparison to other types of SNL’s. We also reported the unique behavior of the SNL system in the MI dynamics. Following the MI analysis, the proceeding section deals with the supercontinuum generation (SCG) process by virtue of MI. We examine exclusively the impact of each form of SNL on the SC spectrum and predicted numerically that exponential case attains the phase matching earlier and thus enable to achieve broad spectrum at a relatively shorter distance of propagation than the other cases of SNL’s. Thus a direct evidence of SCG from MI is emphasized and the impact of SNL in MI-SCG is highlighted. To analyze the quality of the output continuum spectrum, we performed the coherence analysis for MI-SCG in the presence of SNL.