A simplified technique for efficient fiber-polymer-waveguide power coupling using a customized cladding with tunable index of refraction

A novel technique to minimize the mode mismatch between the fiber and waveguide modes in integrating optical fiber to polymer waveguides is presented. The mode fields at the facets of the waveguides were tailored, optimizing the waveguide geometry as well as tuning the index of refraction of the lower cladding near the facets, by chemical composition. No additional processes were required after the core was deposited. The modified lower cladding can be integrated efficiently with any other lower-cladding material used in the remaining portion of the waveguide, resulting in hybrid waveguides. A power-coupling loss as low as 0.46 dB at the fiber-waveguide interfaces was demonstrated with the available fiber.