Methods for producing optical fiber by focusing high viscosity liquid

Abstract

The invention is directed to the production of optical fibers from optical fiber preforms using flow physics. The present methods provide for the “drawing” of an optical fiber preform using focusing of the preform by a surrounding fluid, e.g. a heated gas.

1 - 28 . (cancel).  
     
     
         29 . A method of producing a fiber from a cylindrical preform, comprising the steps of: 
 heating a first end of a cylindrical, ductile, preform in a pressure chamber wherein the preform has a first lateral dimension along a longitudinal axis;    applying physical pressure to the heated first end by flowing a focusing gas along a portion of the longitudinal axis of the preform, wherein the focusing gas is caused to flow in a direction along the preform and toward the first end of the preform so that the first end of the ductile preform is accelerated by tangential sweeping forces exerted by the focusing gas thereby forming a fiber with a decreased lateral dimension relative to the first lateral dimension of the preform.    
     
     
         30 . The method of  claim 29 , wherein the focusing fluid is heated.  
     
     
         31 . The method of  claim 29 , wherein the preform is comprised of silica glass.  
     
     
         32 . The method of  claim 29 , wherein the preform is an optical fiber preform comprised of silica.  
     
     
         33 . The method of  claim 29 , wherein the cylindrical preform is a solid cylinder comprising silica glass and is expelled from the exit opening as a solid cylindrical fiber.  
     
     
         34 . The method of  claim 29 , wherein the cylindrical preform is a hollow cylinder comprising silica glass and is expelled from an exit opening of a pressure chamber as a hollow cylindrical fiber.  
     
     
         35 . The method of  claim 29 , wherein the gas is heated inert gas and the gas exits an exit opening of a pressure chamber at supersonic speed.  
     
     
         36 . The method of  claim 29 , wherein the ductile preform is drawn through a nozzle which nozzle begins as an opening inside a pressure chamber and extends along a curved surface, ending at an exit opening of the pressure chamber.  
     
     
         37 . The method of  claim 36 , wherein the curved surface of the nozzle has a surface configuration with a nozzle parameter geometry defined by an equation  
         p ( x )= p   0   e   −λx   where p(x) is a curve defining function which plots the nozzle geometry, ρ 0  is the internal pressure of the focusing gas as it enters the nozzle, λ is greater than 0.635 to obtain supersonic speed for the focusing gas and x is a function.    
     
     
         38 . The method of  claim 37  where λ is 2.0 or more.  
     
     
         39 . The method of  claim 37  where λ is about 5.65.  
     
     
         40 . The method of  claim 36 , wherein the equation  
       
         
           
             
               
                 P 
                 0 
               
               ≥ 
               
                 
                   
                     μ 
                     l 
                   
                    
                   
                     V 
                     1 
                   
                 
                 L 
               
             
           
           
           
               
           
         
         applies and P 0  is the pressure at an entrance port to the pressure chamber; μ l  is the viscosity of the ductile preform end, V 1  is the velocity of the fiber in the nozzle and L is the length of the nozzle.  
       
     
     
         41 . A method of producing a fiber from a molten viscous liquid; comprising the steps of: 
 extruding a stream of a molten viscous silica glass in a manner so as to flow from a supply source into a pressure chamber wherein the stream has a first circumference;    supplying a focusing gas to the pressure chamber whereby the gas enters through an entrance port of the pressure chamber and exits through an exit port of the pressure chamber positioned downstream of the flow of the stream of molten viscous silica glass;    wherein the gas surrounds the stream of molten viscous silica glass and compresses the first circumference creating a narrowed stream of a second circumference narrower than the first circumference, which narrowed stream is expelled from the exit port of the pressure chamber as a fiber of silica glass.    
     
     
         42 . The method of  claim 41 , wherein the gas is a heated inert gas and the gas exits the exit opening of the pressure chamber at supersonic speed.  
     
     
         43 . The method of  claim 42 , wherein the stream of molten silica glass flows through a nozzle which nozzles begin as an opening inside the pressure chamber and extends along a curved surface ending at the exit port of the pressure chamber.  
     
     
         44 . The method of  claim 43 , wherein the curved surface of the nozzle has a surface configuration with a nozzle parameter geometry defined by an equation  
         p ( x )= p   0   e   −λx   where p(x) is a curve defining function which plots the nozzle geometry, ρ 0  is the internal pressure of the focusing fluid as it enters the nozzle, λ is greater than 0.635 to obtain supersonic speed for the focusing fluid and x is a function.    
     
     
         45 . The method of  claim 44  where λ is 2.0 or more.  
     
     
         46 . The method of  claim 44  where λ is about 5.65.  
     
     
         47 . The method of  claim 44 , wherein the equation  
       
         
           
             
               
                 P 
                 0 
               
               ≥ 
               
                 
                   
                     μ 
                     l 
                   
                    
                   
                     V 
                     1 
                   
                 
                 L 
               
             
           
           
           
               
           
         
       
       applies and P 0  is the pressure at an entrance port to the pressure chamber; μ l  is the viscosity of the ductile preform end, V 1  is the velocity of the fiber in the nozzle and L is the length of the nozzle.  
     
     
         48 . A method of producing an optical fiber preform element, comprising the steps of: 
 providing a hollow tube having a longitudinal axis;    applying physical pressure to force the tube through a feeding source in a manner which causes the preform to be expelled from an exit opening of the channel in a longitudinal manner; and    forcing a fluid through a pressure chamber in a manner which causes the fluid to exit the pressure chamber from an exit orifice in front of a flow path of the preform expelled from the exit opening of the channel,    wherein the fluid surrounds said preform and focuses said preform in a longitudinal manner to expel an optical fiber from said pressure chamber.    
     
     
         49 . A device for producing a fiber, comprising: 
 a pressure chamber comprising an entrance port for adding a focusing fluid and an exit port for expelling a viscous liquid; and    a nozzle positioned in the exit port, the nozzle comprising a curved surface with a geometry defined by an equation      p ( x )= p   0   e   −λx     where p(x) is a curve defining function which plots the nozzle geometry, ρ o  is the internal pressure of the focusing fluid as it enters the nozzle, λ is greater than 0.635 to obtain supersonic speed for the focusing fluid and x is a function.