A theoretical analysis of soliton pair conversion with variable coefficients in all-optical communications

We investigate the dynamics of ultrashort pulses in a real-world system featuring periodically distributed dispersion and nonlinearity. We present a precise solution resembling a chirped soliton for the higher-order nonlinear Schrödinger equation (HNLS). This solution incorporates group velocity dispersion (GVD), stimulated Raman scattering (SRS), a third-order dispersion (TOD) term, cubic nonlinear effects and self-steepening (SS) effects with spatially varying coefficients. The derivation is based on specific parametric conditions, accounting for both linear and nonlinear absorption and amplification. The investigation reveals the stability of solitary-like solutions as they propagate over long distances in the medium. Additionally, we furnish parametric conditions that dictate the existence of chirped solitons. The numerical results closely corroborate the outcomes obtained through analytical approaches. (author)