  Nonlinear waves that collide with localized defects exhibit complex behavior.
Apart from reflection, transmission, and annihilation of an incident wave, a
local inhomogeneity can activate internal modes of solitons, producing many
impressive phenomena. In this work, we investigate a two-dimensional
sine-Gordon model perturbed by a family of localized forces. We observed the
formation of bubble-like and drop-like structures due to local internal shape
modes instabilities. We describe the formation of such structures on the basis
of a one-dimensional theory of activation of internal modes of sG solitons. An
interpretation of the observed phenomena, in the context of phase transitions
theory, is given. Implications in Josephson junctions with a current dipole
device are discussed.
