Self-trapping of spatially and temporally incoherent white light in a photochemical medium.

We report that a beam of spatially and temporally incoherent white light self-traps by initiating free-radical polymerization in an organosiloxane medium. Refractive index changes due to polymerization lead to the formation of a narrow channel waveguide that traps and guides the entire multimode, broadband beam without diffraction. The response time of the system, which is determined by the inherently slow rate of free-radical polymerization, exceeds by several orders of magnitude the femtosecond-scale random phase fluctuations that characterize white light. Self-trapping of incoherent light is possible in the photochemical medium because it responds to the time-averaged intensity profile of the white light beam.