Vertically coupled glass microring resonator channel dropping filters

Air-clad glass microring resonators vertically coupled to buried channel wa veguides are experimentally investigated. Ring radii of 10 mu m, and channe l drop bandwidths of 5 nm are reported, Vertical coupling eliminates the ne ed for the etching of fine features, and relaxes the alignment of the reson ator with respect to the input and output bus waveguides.