Wavelength division action of a distributed single-mode fiber-to-symmetrical planar waveguide coupler

Light transfer between a curved single-mode fiber and a planar waveguide is investigated experimentally in dependence on the light wavelength and for different refractive indices and thicknesses of the planar waveguide and for different polishing depths. A coupled mode model is applied to describe the coupler behavior, leading to a very good agreement with the experimental results. The action of the coupler as a narrowband filter and long pass edge filter is revealed.<>