Nature of the parametrically excited bound soliton state

The internal dynamics of the parametrically excited bound state of double solitons is explored, in particular, the periodic "collision" behavior of the identical solitons. The results reveal the collapse-recreation mechanism of the endless "collisions," in which momentum of each soliton always flows toward the symmetric center of the state. It is also found that damping dissipation plays an important role in maintaining the regular dynamics of "collisions." In weakly dissipative media, the parametric excitation of some other internal oscillation mode of high frequency can have the soliton-soliton interaction irregular, or can even break the spatial symmetry. [S1063-651X(98)07711-3].