Tandem light bullets

We put forward a novel strategy to achieve formation of fully three-dimensi onal light bullets. The new scheme is based on tandem structures where nonl inearity and group-velocity dispersion required for the self-trapping of li ght are spatially distributed, opening the door for the possibility that th ey are not necessarily contributed by the same crystal. We show that multic olor light bullets do exist for a variety of tandems with feasible domain l engths. (C) 2001 Elsevier Science B.V. All rights reserved.