  We consider theoretically two coupled optical waveguides with a varying
barrier height along the waveguides direction. The barrier could be constructed
by the elongated island with a reduced refractive index (which acts as a
potential barrier), such that in the middle region it splits a waveguide into
two weakly coupled parts. It is predicted by numerical simulations and
analytical consideration that the presence of some imperfection of the system
parameters can cause splitting of injected laser beam and one will observe two
intensity maximums at the output, while for small imperfections the input and
output beam intensity distributions will be the same. The switching between two
regimes could be achieved changing spectral width of the beam or refractive
index of the island. This nontrivial effect is explained by possibility of
transitions between the different eigenstates of the system in the region of
large potential barrier heights. The mentioned effect could be used for
all-optical readdressing and filtering purposes.
