Dromion Excitations in Self-Defocusing Optical Media

We investigate the nonlinear dynamics of multi-dimensional optical pulses propagating in an isotropic self-defocusing medium. Using a method of multiple-scales we show that the nonlinear evolution of the pulses is governed by Davey-Stewartson equations. Dromion-like nonlinear localized structures (high-dimensional optial solitons) excited from a continuous wave background and decaying in all spatial directions are predicted through the interaction between a wave-packet superposed by short-wavelength components and a long-wavelength mean field generated by an optical rectification.