FIBER OPTIC POWER SPLITTER

摘要

Fiber optic splitters having a central fiber (18, 21) and a selectable number of surrounding fibers (10, 20) with mutual contact among the surrounding fibers and central fiber, formed preferably of identical diameter starting fibers. According to a formula, between three and five surrounding fibers, the central fiber (18, 21) has a reduced diameter, while for seven or more surrounding fibers, the diameters of the surrounding fibers are reduced. Splitters with one input and four, eight, twelve, or sixteen equal outputs, having a flattened wavelength response are provided. Means are provided to reduce detrimental phase mismatch at the desired coupling ratio as by substantially matching the propagation constants of the central and surrounding fibers in the finished coupler. Provisions for sufficiently matching the propagation constants include making the fused splitter region short; starting with fibers having differing propagation constants selected so the difference is diminished during fusing; fusing the fibers together to the extent that there are substantially no interstitial voids in the coallesced fiber mass; and surrounding the surrounding fibers (10, 20) with a transparent substance having the effect of cladding. For the latter purpose, a tube (11) or transparent optical rods assembled about the surrounding optical fibers are fused therewith, or the transparent substance is a moldable substance applied after the fused region of the coupler has been formed.