Active alignment of optical fibers to planar waveguides using a thermal-curing adhesive

This paper described a process that was developed for the active alignment of optical fibers to planar waveguides using a thermal-curing adhesive, in order to improve the performance and reliability of waveguide-based components. The process combines alignment at a temperature selected for adhesive curing with offline postthermal treatment of the aligned device that is suitable for volume manufacturing. A specially designed fiber-array holder and a waveguide-device holder were used to overcome the effects of temperature and stress on the alignment, simplifying the alignment from high temperature to room temperature. By studying the adhesive curing kinetics and the buildup of adhesive bonding strength, the alignment was tuned to balance performance and efficiency. Using this alignment process, fiber-to-waveguide couplings that provide low optical loss, strong bonding, and excellent reliability were achieved.