Scattering of the total field from the slow-tapered and step-like discontinuities of dielectric waveguides

The spatial transient regimes of the total field propagation in irregular o ptical fibers are considered. The propagation of a linearly polarized, axia lly symmetric mode through the cutoff cross section in a down-tapered fiber , as well as the scattering from the step-like and smooth discontinuities,a r simulated by the finite-difference beam propagation method applied to sol ve the paraxial scalar wave equation. Kerr-like nonlinearity, as well as ab sorption losses of the fiber material, are shown to influence the transmitt ance of th structure. (C) 2000 John Wiley & Sons, Inc.