Highly efficient full-vectorial 3-D BPM modeling of fiber to planar waveguide couplers

The behavior of a fiber-slab coupler used as a polarization and wavelength tunable filter is studied both experimentally and theoretically. The theoretical model is based on a three-dimensional (3-D) fully vectorial beam propagation 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 comparisons among experimental and theoretical two-dimensional (2-D) and 3-D numerical modeling are reported and discussed. They show a very good agreement in the 3-D case where field polarization, coupling terms and z-variant structures are taken into account.