  We study the polarization properties of elliptical femtosecond-laser-written
waveguides arrays. A new analytical model is presented to explain the asymmetry
of the spatial transverse profiles of linearly polarized modes in these
waveguides. This asymmetry produces a polarization dependent coupling
coefficient, between adjacent waveguides, which strongly affects the
propagation of light in a lattice. Our analysis explains how this effect can be
exploited to tune the final intensity distribution of light propagated through
the array, and links the properties of a polarizing beam splitter in integrated
optical circuits to the geometry of the waveguides.
