Bright solitons and repulsive in-phase interaction in media with competing nonlocal Kerr nonlinearities

We present new features of 1D bright solitons in the phenomenological propagation model combining competing focusing and defocusing nonlinearities with different nonlocal lengths. It has been shown that the interplay between the two nonlocal nonlinearities results in new soliton properties, including modifications of the soliton stability and variable character of the in-phase soliton interaction. In particular, an unstable composite type soliton comes to exist and serves as a transition point distinguishing repulsion from attraction behaviors in the interactions of two separate solitons. The existence of competing nonlocal nonlinearity in synthetic metamaterials synthesized from materials with different diffusive media may be possible and has indeed been experimentally confirmed for a strongly temperature dependent liquid crystal (see Warenghem et al 2008 J. Opt. Soc. Am. B 25 1882–7)