Propagating solitons generated by localized perturbations on the surface of deep water

We report experimental evidence of the propagating capillary solitary waves generated by a localized water surface perturbation. Solitons are formed at the air-water interface with a solid plunger and then propagate with velocities proportional to their amplitudes. The shape of the forward front of such solitons is independent of the plunger shape and is given by the hyperbolic secant profile. We find that the nonlinearity of capillary waves is responsible for a small dispersion in the capillary wave group velocity and the soliton existence. This dispersion can be further reduced by adding minute concentrations of proteins to water.