Accurate Silicon Spacer Chips for an Optical-Fiber Cable Connector

Low-loss multifiber splices have been obtained with the use of accurate silicon spacer chips. These spacer chips are used in a unique splicing technique developed by Bell Laboratories 1 and used in the Atlanta Fiberguide experiment. This multifiber cable splice is a stacked array consisting of two properly prepared cable connectors butted end to end. A cable array connector is a laminate sandwich of silicon alignment chips with "V" grooves on both top and bottom surfaces interleaved with optical fibers epoxied to form a two-dimensional array (Fig. 1). A completed connector may consist of up to 144 optical fibers positioned by up to 13 alignment chips. Each fiber in the array must be positioned accurately to its counterpart in a mating array to obtain low splice loss. The transverse misalignment of the mating fibers should be no greater than one-tenth the core radius or typically 2.5 micrometers. 2,3 This can only be obtained with alignment chips having high dimensional accuracy with respect to thickness, groove geometry, and position. The feasibility of the multifiber splice was shown with alignment chips manufactured of aluminum. The aluminum chip, however, could not be manufactured repeatedly with the high dimensional accuracies required. An improved chip was developed, that met the above goals, using (100) oriented silicon4 and photolithographic techniques. This improved chip has demonstrated a significant reduction in the overall array splice loss. 91