Comment on ″Optical soliton to multi-core (coupling with all the neighbors) directional couplers and modulation instability″ [Eur.Phys.J.Plus(2021)136:325]

Abstract

AbstractIn a recent paper, Abbagari et al. (EPJP 136:325, 2021) investigated the nonlinear multi-core coupler (coupling with all neighbors) with the parabolic law nonlinearity via the so called new sub-ODE method. In this comment, we show that all solutions presented by Abbagari et al. (EPJP 136:325, 2021) do not satisfy the considered equation and therefore are incorrect. Some important attentions to the authors (EPJP 136:325, 2021) have been presented.