Interaction of Bragg grating solitons in a cubic-quintic medium

We investigate the interaction of Bragg grating solitons in a cubic-quintic nonlinear medium. In a previous work two different families of solitons have been identified in such a medium, which are separated by a border 1 - omega = 27/(160v), where -1 < omega < 1 is the frequency and nu > 0 controls the strength of quintic nonlinearity. We find that two zero-velocity solitons belonging to the region 1 - omega < 27/(160nu) with initial phase difference of zero (i.e. Deltaphi = 0) attract each other and when Deltaphi = pi and pi/2 the solitons repel each other. When Deltaphi = 0, for certain parameter values, the interaction results in a sincle zero velocity soliton. But in many cases two moving solitons emerge as a result of interaction. The interaction of solitons belonging, to the region 1 - omega > 27/(160v) is similar to the other family in that when Deltaphi = 0 they attract, and they repel when Deltaphi = pi and pi/2. However, in the case of Deltaphi = 0 and pi/2 the interaction always results in the deformation and subsequent destruction of solitons.