It is shown that, as a result of diffusion space-charge field effects,
self-bouncing beam behavior is possible in photorefractive waveguides
. The process is explicitly demonstrated by means of an exact Gaussian
solution in the case of parabolic planar waveguides. The trajectory o
f these beams as well as their associated characteristics is given in
terms of relevant parameters. Asymmetric modal states are also obtaine
d for parabolic and other waveguide structures. (C) 1996 Optical Socie
ty of America