Controllable propagation paths of gap solitons.

This paper numerically investigates the evolution of solitons in an optical lattice with gradual longitudinal manipulation. We find that the stationary solutions (with added noise to the amplitude) keep their width, profile, and intensity very well, although the propagation path is continuously changing during the modulated propagation. Discontinuities in the modulation functions cause the scattering of the beam that may end the stable propagation. Our results reveal a method to control the trajectory of solitons by designed variation of the optical lattice waveguides. Interesting examples presented include the snakelike and spiraling solitons that both can be adaptively induced in sinusoidally and helically shaped optical lattices. The controlled propagation paths provide an excellent opportunity for various applications, including optical switches and signal transmission, among others.