We investigate a system of two waveguides with leaky modes sharing a c
ommon substrate (radiatively coupled waveguides). The main advantage o
f such a system is the possibility of remote coupling. A perturbation
theory is developed for both TE and TM polarization. Numerical calcula
tions of dispersion curves and of the coupling length allow us to dete
rmine the limitations of the perturbation theory. We study the influen
ce of multimode interference on the process of beating by considering
the propagation of a given initial field. Finally, we propose a new de
sign for an effective, integrated optical TE-TM polarization splitter.
(C) 1997 Optical Society of America