Metallization of optical fibers

Abstract

A method is disclosed for the metallization of optical fibers with improved adhesion while using a shorter process cycle.

1 . A process for metallizing a silica surface of an optical fiber, said process comprising: 
 (i) contacting said silica surface with an aqueous colloidal composition comprising stannous chloride, palladium chloride and hydrochloric acid; and    (ii) depositing at least one metal layer on the surface obtained in (i).    
     
     
         2 . The process according to  claim 1 , wherein said metal layer is deposited electrolessly.  
     
     
         3 . The process according to  claim 1 , wherein the metal layer is deposited electrolytically.  
     
     
         4 . The process according to  claim 2 , wherein the metal layer is nickel.  
     
     
         5 . The process according to  claim 1 , wherein the metal layer is copper.  
     
     
         6 . The process according to  claim 5 , wherein the metal layer is deposited electrolessly.  
     
     
         7 . The process according to  claim 1 , wherein the formation of the metal layer in step (ii) is followed by deposition of at least one more metal layer.  
     
     
         8 . The process according to  claim 1 , wherein the metal layer is Ni—B.  
     
     
         9 . The process according to  claim 1 , wherein the surface obtained in (i) is contacted with an aqueous accelerating solution.  
     
     
         10 . The process according to  claim 8 , wherein the accelerating solution comprises ammonium bifluoride dissolved in water.  
     
     
         11 . A colloidal catalyst composition for use in plating optical fibers, comprising inorganic fluorides in addition to water, stannous chloride palladium chloride and hydrochloric acid.  
     
     
         12 . A method for metallizing a silica surface of an optical fiber comprising the following steps: 
 (a) cleaning the surface of the exposed optical fiber, so as to eliminate contaminants from the surface of the optical fiber;    (b) contacting the optical fiber with a single sensitizing composition comprising stannous chloride, palladium chloride and hydrochloric acid; where the sensitizing solution may optionally contain fluorides;    (c) contacting the fiber obtained in step (b) with an accelerating solution;    (d) exposing the optical fiber obtained in step (c) to at least one electroless metal step and/or to at least one electroplating metal step to deposit at least one metal layer, said metal being selected from Ni, Cu, Ni/Cu, Ni/Co, Ni/Pd and combinations thereof, and    (e) plating a top metal layer, such metal layer comprising a metal or metal alloy selected from Au, Pd, Ni/Pd and Pt.    
     
     
         13 . The method according to  claim 12 , where the metallization in step (d) is carried out by electroless deposition.  
     
     
         14 . The method according to  claim 12 , where the metalization in step (d) is carried out by electroplating.  
     
     
         15 . The method according to  claim 12 , further comprising after step (d) and before step (e) a step of heating the metal-plated optical fiber.  
     
     
         16 . Optical fiber metallized by the method of  claim 1 .  
     
     
         17 . Optical fiber metallized by the method of  claim 12 .  
     
     
         18 . A method for depositing a tin- palladium layer on a silica surface of an optical fiber, said method comprising contacting said silica surface with an aqueous colloidal composition comprising stannous chloride, palladium chloride and hydrochloric acid, so as to obtain a silica surface coated with a layer comprising tin-palladium particles.  
     
     
         19 . The method of  claim 18 , further comprising rinsing with water said coated silica surface and drying so as to obtain a dry layer comprising tin-palladium particles.  
     
     
         20 . The method of  claim 18  or  19 , wherein said layer is colored.  
     
     
         21 . Optical fiber processed by method of  claim 19.