Optical fiber assemblies, and methods and apparatus for the manufacture thereof

Abstract

Methods for manufacturing cables and cables assemblies include providing powder particles within a tube extruded about optical fiber. The particles may be accelerated so that as they strike the tube and mechanically attach to the tube.

What is claimed is: 
     
         1 . A fiber optic cable, comprising:
 optical fibers;   tubes formed from a polymer material, wherein the tubes each support a subset of the optical fibers therein;   a jacket having an interior defining a cavity through which the tubes extend; and   powder particles disposed about an inner wall of each of the tubes with at least a portion thereof mechanically attached to the inner wall of the tubes such that portions of the powder particles are lodged in or embedded in the inner wall, extending into the inner wall, and other portions of the powder particles protrude outward beyond the surface of the inner wall, and wherein the attachment is such that less than all of the surface area of the inner wall of the tube is covered by the powder particles.   
     
     
         2 . The cable of  claim 1 , wherein the mechanical attachment is such that the powder particles are generally uniformly disposed on the surface of the inner wall of each tube, and wherein about 30 percent or less of the surface area of the inner wall has powder particles mechanically attached thereto. 
     
     
         3 . The cable of  claim 1 , wherein the powder particles are positioned directly between the optical fibers and the respective tube such that the powder particles act as a separation layer inhibiting sticking between the optical fibers and the tube during manufacturing of the tube, while the tube is molten; and wherein the powder particles act as a slip layer between the optical fibers and the tube, reducing friction between the inner wall of the tube and the optical fibers, whereby the tube is free of gel, grease, yarn, and tape. 
     
     
         4 . The cable of  claim 1 , wherein the tubes are loose-fitting tubes, the cable further comprising a central strength member, wherein the tubes are arranged around the central strength member. 
     
     
         5 . The cable of  claim 1 , wherein the powder particles comprise super-absorbent polymer, wherein the powder particles have an average particle size of about 60 micrometers or less, and wherein the absorption capacity of the powder particles is at least 100 grams per gram of powder particles. 
     
     
         6 . The cable of  claim 5 , wherein the superabsorbent polymer comprises at least one of cross-linked sodium polyacrylate and a copolymer of acrylate and polyacrylamide. 
     
     
         7 . The cable of  claim 1 , wherein the powder particles comprise flame retardant particles. 
     
     
         8 . The cable of  claim 7 , wherein the flame retardant particles comprise at least one of aluminum trihydrate and magnesium hydroxide. 
     
     
         9 . The cable of  claim 1 , wherein a normalized concentration of powder particles in each tube is less than 0.01 grams per meter per square millimeter of tube inner cross-sectional area. 
     
     
         10 . The cable of  claim 1 , wherein an average particle size of the powder particles is between 20-40 microns.