Optical fiber coupler array

Abstract

An optical fiber coupler array capable of providing multiple low loss, high coupling coefficient interfaces between a predetermined number of low numerical aperture optical fibers and an optical waveguide device with at least a corresponding number of waveguide interfaces. The novel coupler array includes a plurality of coupler inner cores and a plurality of corresponding coupler outer cores, within a medium surrounding each plural outer core, and also includes a first end for interfacing with plural optical fibers and a second end for interfacing with a plurality of waveguide interfaces of an optical waveguide device. The sizes of the inner and outer cores are gradually reduced from the first end to the second end in accordance with at least one predetermined reduction profile. Various parameters, such as refractive indices and sizes of the inner and outer cores and the medium (as well as the reduction profile) are selected to produce a plurality of low numerical aperture waveguides at the first end, and a plurality of high numerical aperture waveguides at the second end, while advantageously minimizing insertion loss and maximizing the coupling coefficient at each end. Advantageously, the novel coupler array may be fabricated as an array of individually drawn couplers from multiple parallel fused performs (arranged in a row, or in another geometric cross section). Alternately, the novel coupler array may be fabricated from a single perform (glass or polymer) embedded with a plurality of parallel inner and outer core sets.