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In this paper, modulation instability and nonlinear supratransmission are investigated in a one-dimensional chain of atoms using cubic–quartic nonlinearity coefficients. As a result, we establish the discrete nonlinear evolution equation by using the multi-scale scheme. To compute the modulation instability gain, the linearizing technique is employed. The effect of the higher nonlinear component on modulation instability is particularly examined. Following that, full numerical integration was performed to identify modulated wave patterns as well as the appearance of a rogue wave. Through the nonlinear supratransmission phenomenon, one end of the discrete model is driven into the forbidden bandgap. As a consequence, for driving amplitudes above the supratransmission threshold, the bright soliton and modulated wave patterns are satisfied. An important behavior is observed in the transient range of time of propagation when the bright soliton wave turns into a chaotic soliton wave. These results corroborate our analytical investigations on the modulation instability and show that the one-dimensional chain of atoms is a fruitful medium to generate long-lived modulated waves. [ABSTRACT FROM AUTHOR]

In this paper, we considered a discrete coupled nonlinear Schrödinger equations (CNLSEs) which describes the propagation of solitonic waves in a gyrotropic molecular chain (GMC) of left and right circularly polarized intramolecular vibrations. From the linear analysis, we shown the forward and backward waves for left and right-handed modes. We underlined the effects of the gyrotropy term and effective mass (EM) on both modulation instability (MI) gain and modulated wave (MW) pattern. It reveals for strong enough values of these parameters that the generation of new sides lobes and MI bands. For numerical simulation, we shown out the propagation and interaction of the MW bright-soliton with high energy on the peak. It results from this investigation that gyrotropy term and EM behave as being energy sources in GMC. Finally, the reported outcomes can be used during the transfer of energy in molecular chain. • We studied discrete coupled nonlinear Schrodinger equations. • These equations describe the propagation of solitonic waves in a gyrotropic molecular chain. • We exhibited the discrete solitons interaction in the gyrotropic molecular chain • We investigated the effects of gyrotropy term and effective mass on the modulated waves. • The linear analysis and modulation instability are provided. [ABSTRACT FROM AUTHOR]

• The vertical grain displacement model is presented. • The acquired results are given by some figures. • The modulation analysis is given. • Bright, dark and singular optical solitons are presented. The paper concerns envelope soliton propagating through the nonlinear transverse dust grain displacement in dusty plasma crystals. The work found its motivation from the recent paper of the authors [7]. To reach the goal of this study we establish the linear dispersion and the nonlinear Schrödinger equation (NLSE) by employing the quasi discrete approximation [7,13–15]. Contrary to ref. [7] , it is observed one additional regime of the formation of the dark soliton while choosing the gap frequency value (ω g ≈ 150 sec −) which is close to the experimental value given by Motcheyo et al. [7] , Tsopgue et al. To corroborate the prediction made analytically to group velocity, was confirmed by numerical and experimental studies. As, it is established that in general manner the modulated waves describing by the NLSE can be stable or unstable to the perturbation, the modulation instability of steady state have been done. Despite, that the bandwidth of the model has been reduced compared to [7,13–15] , we can say without hesitation that this work will be a capital contribution in dusty plasma crystal. [ABSTRACT FROM AUTHOR]

• The Heisenberg ferromagnetic spin chain is studied. • The bright, dark, combined and rational optical solitons are constructed. • The modulation instability analysis is presented. • The obtained solutions are presented by 2D and 3D figures. In this paper we utilize the auxiliary equation method to show the leverage of the fractional derivative parameter and the Magnetic Coupling Coefficients (MCC) on the procured soliton solutions and the Modulation Instability (MI) gain in Heisenberg ferromagnetic spin. The pedestal of the work is set on the (2 + 1)-fractional time order dimensional Heisenberg ferromagnetic spin chain equation which demonstrate the propagation of nonlinear waves in Heisenberg ferromagnetic spin chain system. The results collected have enclosed bright-dark soliton, dark soliton and rational solutions. Compared the acquired results with Zhao et al. (2016) [26], Akbar (2021) [27], Hosseini et al. (2021b) [28], further soliton-like solutions have been drop in and the marvel of the fractional parameter has been exposed across the spatiotemporal and plot evolution of the bright and dark soliton solutions. Therewith, the MI bands have been stressed and it is observed some new attitude of the MI gain spectra under the induction of the MCC jointed with the fractional time derivative order. The collected results are new in literature in our knowledge and will give the pipe to the solitary waves theory in Heisenberg ferromagnetic spin including inhomogeneity parameters. [ABSTRACT FROM AUTHOR]

The detection of the solitons whose the propagation is spatially localized on the array is an interesting feature for experimental purposes. Here, we investigate the effect of position-modulated self-Kerr nonlinearity on discrete soliton propagating in an optomechanical array. The optomechanical cells are coupled to their neighbors by optical channels, and each cell supports the self-Kerr nonlinear term. Modulational Instability (MI) together with numerical simulations are carried out to characterize the behavior of the solitonic waves. It results that the nonlinear term shortens the transient regime of the temporal solitonic waves, which allows the wave propagation to be confined along specific cells. As the nonlinear term increases, the pulsed shape of soliton waves get sharped and highly peaked. For a strong enough value of the nonlinear term, the waves feature chaos-like motion. Owing to these results, the position-modulated self-Kerr nonlinear term manifests itself as being an energy source for the solitonic waves, allowing to the generated solitons to propagate during a long time while acquiring energy. These results shed light on the fact that nonlinear optomechanical platforms could be used to generate long-lived temporal localized solitons and even chaotic solitonic waves, which are good prerequisites for information processing purposes. [ABSTRACT FROM AUTHOR]