Because of short distances of propagation in integrated-optic waveguid
e circuits not only the guided-mode field, but also the radiation fiel
d is confined in the waveguide guiding region. This may influence the
performance of nonlinear guides in comparison with usual guided-mode a
nalysis results. In this paper, for the first time the radiation field
guiding in optical waveguides is proved and studied by means of Beam-
Propagation Method (BPM) simulation.