Optical fiber having water swellable material for identifying grouping of fiber groups

Abstract

An improved optical fiber cable in which the threads that hold the various fiber groups together is made of a water swellable material and is color coded to allow the various fibers of the optical cable to be distinguished from each other. The optical fiber cable, includes a plurality of optical fiber groups, each groups including a plurality of optical fibers; a first water swellable material wrapped around a first group and a second water swellable material wrapped around a second group, wherein the first water swellable material has a color which is different from a color of the second water swellable material so as to allow optical fibers of the first group to be distinguished from optical fibers of the second group; and a sheath holding the plurality of optical fiber groups together. The optical fiber cable further includes a buffer tube in which the plurality of optical fiber groups are disposed arranged such that the sheath surrounds the buffer tube. The optical fibers of the first group have different colors and the optical fibers of the second group have different colors. However, the colors of the optical fibers of the first group are the same as the colors of the optical fibers of the second group. Thus, according to the present invention, it is possible to distinguish between optical fibers having the same color by the manner in which the optical fibers are grouped by the colored water swellable material. Further, instead of using a gel for waterproofing the groups of optical fibers, a water swellable material may be used which is wrapped around the optical fiber groups. Finally, the colored water swellable materials can also be used to form super group units in a cable and to block the ingress of water along the cable core.