The behavior of a fiber-slab coupler used as a polarization and wavelength
tunable filter is studied both experimentally and theoretically. The theore
tical model is based on a three-dimensional (3-D) fully vectorial beam prop
agation method (BPM), whose main features concern its high efficiency from
the point of view of memory and central processing unit (CPU) requirements.
The device characteristics have been measured and the results of the compa
risons among experimental and theoretical two-dimensional (2-D) and 3-D num
erical modeling are reported and discussed. They show a very good agreement
in the 3-D case where field polarization, coupling terms and z-variant str
uctures are taken into account.