Asymmetrical star coupler for optical fiber systems

Abstract
A technique has been developed for fabricating M × N fiber couplers that use different core-size fibers to improve the interconnection efficiency of multiterminal optical fiber systems. Experimental results are described for a 2 × 8 transmissive asymmetrical star coupler using 125-μm core diam input fibers and 63-μm core diam output fibers. This construction procedure also has the important advantage of improving the fiber throughput uniformity of fused biconical taper multiport couplers.