The fascination and importance of multicolor solitons is twofold. For one, they offer a truly unique laboratory for soliton phenomena: multicolor solitons exist in the spatial and the temporal do- mains; they exist in guided and in bulk media; they exist in any physical dimensions and thus have the potential to form three-dimensional light bullets; they exist
in continuous as well as in discrete physi-
cal settings; and they are the realization of
a universal phenomenon in nature, name-
ly, the nonlinear parametric mixing of
waves. Second, multicolor solitons offer
clean, robust, stabilized, particlelike pulses.
These beams could play key roles in future passive or active, single-pass or cavity, multifrequency photonic devices for which the price of operation at high-peak power is offset by the unique features of the soliton light spots.