Modulational stability and gap solitons of gapless systems: Continuous versus discrete limits

Matteo Conforti (1) , Costantino de Angelis (2) , T. R Akylas (3) , Alejandro B Aceves (4)

1 Dipartimento di Ingegneria dell'Informazione [Brescia]
2 Department of Information Engineering [Brescia]
3 MIT-MECHE - Department of Mechanical Engineering [Massachusetts Institute of Technology]
4 SMU - Southern Methodist University

We consider a model consisting of two subsystems with crossing linear dispersion curves that describes, for example, light propagation in binary waveguide arrays. This model admits bright-dark gap solitons in both the discrete and the continuous (long-wavelength) limits, in spite of the absence of a gap in the linear (i.e., plane-wave) spectrum. We find that these solitons are always modulationally unstable in the continuous limit, whereas they can be stable in the discrete system if the amplitude of the background component exceeds a certain threshold.

Domaines: Optique [physics.optics]; Formation de Structures et Solitons [nlin.PS]

Matteo Conforti, Costantino de Angelis, T. R Akylas, Alejandro B Aceves. Modulational stability and gap solitons of gapless systems: Continuous versus discrete limits. Physical Review A : Atomic, molecular, and optical physics [1990-2015], 2012, 85 (6), ⟨10.1103/PhysRevA.85.063836⟩. ⟨hal-02394987⟩