Abstract: Optical fiber cables have an inner sheath extruded or otherwise applied to surround optical fibers. If the fibers are coupled to the sheath, substantial shrinkage of the sheath during manufacturing induces microbending losses in the optical fibers. The inventive technique involves choosing a sheath material having a low viscoelastic modulus, typically PVC, and the application of tension thereto during or after extrusion that prevents such shrinkage. This approach typically avoids the necessity of including longitudinal compressive strength members in the cable. A filled optical fiber cable having a flexible gel to prevent water entry advantageously uses the present technique.

Abstract: A single mode optical fiber ribbon cable is disclosed. In preferred embodiments, the cable comprises a filling compound having a critical yield stress less than about 70 Pa at 20.degree. C. and/or fibers having a coating that comrises a low modulus (less than about 1.5.multidot.10.sup.6 Pa at 20.degree. C.) inner coating and a high modulus (more than 10.sup.8 Pa at 20.degree. C.) outer coating. Communication cable according to the invention can have low cabling loss, is adapted for array joining, can have high fiber density, and can advantageously be used in short-haul applications such as for metropolitan trunk lines or loop, as well as for long-haul applications.

Abstract: The forward scattering pattern from a transversely-illuminated polymer-coated optical fiber can be used to insure well-centered coatings on optical fibers. A simple interpretation of the scattering pattern provides an error signal to guide compensatory coating cup alignment. For polymers coating materials with a refractive index higher than that of silica, the scattering pattern contains caustic surfaces. If the coating is eccentric in a direction perpendicular to the incident rays, the positions of the caustic surfaces vary monotonically with eccentricity.

Abstract: In order to organize a plurality of fiber lightguides (33--33) into a planar array (40), so that they can be bonded together between two tapes (34--34) to form a ribbon (32), the fiber lightguides are payed out from individual supply spools (51--51) and advanced toward a takeup (43). Interposed between the supply spools and the takeup is at least one surface (72) past which the lightguides are advanced and which is effective to organize them contiguously into a single layer array (76). The surface is made with a curvature which is convex in the direction of advance of the fiber lightguides and which is concave in a direction transverse to the direction of advance. The single layer array (76) is advanced past and in engagement with another surface (86) which reforms the array into a planar configuration after which the lightguides are bonded together to form the ribbon (32).

Abstract: Microbending loss is reduced and abrasion protection is afforded for optical fibers by relatively thick polymer coatings characterized in part by a preferred elastic tensile modulus and cold flow property. The coating process uses rapid cooling of a liquid application to promote rapid gelation or solidification and thus achieve uniform coating diameter without beading. Fibers so coated are formed into ribbon structures having definite center-to-center fiber spacing. Preparation of coated fibers or ribbon structures for splicing is achieved by solvent stripping of the coating.