Coupling between single-mode fiber and polymeric planar thin film waveguide of different structures

Abstract

Coupling between single-mode (SM) fiber half-coupler and polymeric planar waveguide is investigated. Fabrication of fiber half-couplers using a standard polishing block, including a simple arrangement of fixing the fiber on a glass plate with automatic determination of the polished fiber parameters, are shown. Optical power coupled into thin film PMMA and polystyrene waveguides through a uniform coupling region is measured for the cases of matched and mismatched propagation constants in the fiber half-coupler and the waveguides. Also, variation of the coupled power in the thin film waveguide is correlated with the change in temperature for potential use in thermal sensing and switching applications. Characteristics of the SM fiber-to-optical waveguide coupler with a uniform coupling section and the advantages of a tapered or combined uniform and tapered structure of the film waveguide are discussed.