Self-Alignment of Optical Fibers with Optical Quality End-Polished Silicon Rib Waveguides Using Wet Chemical Micromachining Techniques

Abstract—This paper presents a new cost-effective method for self-aligning optical fibers on silicon platforms and for achieving optical quality end-polished silicon-on-insulator (SOI) rib wave-guide devices using wet chemical micromachining techniques. Through accurate alignment to the h011i plane(s) of the (100) device layer of a SOI wafer, rib waveguide devices with self-alignment features are fabricated with the ends of each waveguide wet etched and concurrently polished providing an optical quality facet or fiber-to-waveguide interface. Eliminating the need to saw cut and then mechanically polish the ends of fabricated devices, the overall fabrication process is simplified whilst also providing an integrated optic fiber alignment capability at the ends of the fabricated waveguide devices with an alignment accuracy limited by fiber size tolerance. Experimental measurements were carried out to verify the optical quality of the waveguide facets formed using this new technique which proved excess facet losses of practically unmeasurable quantities. Index Terms—Integrated optics, micromachining, optical pla-nar waveguides, rib waveguides, silicon-on-insulator technology. I