Snakelike nonautonomous solitons in a graded-index grating waveguide

We present a series of analytical solutions which describe nonautonomous solitons in a planar waveguide with an additional periodical structure, that is, a long-period grating. The explicit functions which describe the evolution of the width, peak, and trajectory of the soliton's wave center are presented exactly. The gain parameter has no effects on the motion of the soliton's wave center or its width; it affects just the evolution of the soliton's peak. The grating term affects the motion of the soliton's wave center without changing its shape. The evolution of the soliton under the propagation-distance-dependent gain term is investigated too. It is reported that an arbitrary additional structure can be added on the graded-index waveguide to control the motion of the soliton without affecting its shape.