Critical power for self-focusing in bulk media and in hollow waveguides

We determine the threshold power for self-focusing collapse both in a bulk medium and in a hollow-core waveguide for Various spatial profiles. We find that the threshold power for collapse in the waveguide is always equal to the lower-bound prediction for a bulk medium. (C) 2000 Optical Society of America. OCIS codes: 190.4420, 260.5950, 190.4370.