Highly efficient coupling between single-mode fiber and polymer optical waveguides

Single-mode optical D-fiber is fabricated and coupled to single-mode acrylic waveguides by use of a novel technique utilizing alignment ways and a transcision. The D-fiber is fabricated by lapping the cladding layer of a single-mode fiber to the core. Optical waveguides and alignment ways are made with polymers by photolithography. This technique allows coupling of the optical elements by means of a transcision placed perpendicularly to the optical axis of the waveguide in order to achieve efficient coupling of single-mode fiber to optical waveguides with typical coupling losses of 0.5±0.2 dB with index matching liquid. The technique also allows for passive coupling resulting in an excess loss over active alignment of 0.35 dB. Coupling efficiency results presented here are the highest for single-mode fiber to single-mode optical waveguide. The best coupling produced an efficiency of 97.3% (or 0.12 dB loss)