Method of making optical fibers in a reducing atmosphere

Patent metadata

Field	Value
Publication number	US-2016009589-A1
Application number	US-201514734122-A
Country	US
Kind code	A1
Filing date	Jun 9, 2015
Priority date	Jul 9, 2014
Publication date	Jan 14, 2016
Grant date	—

Abstract

A method for forming an optical fiber preform and fibers drawn from the preform. The method includes forming a soot cladding monolith, inserting a consolidated core cane into the internal cavity, and processing the resulting core-cladding assembly to form a preform. Processing may include exposing the core-cladding assembly to a drying agent and/or dopant precursor, and sintering the core-cladding assembly in the presence of a reducing agent to densify the soot cladding monolith onto the core cane to form a preform. The preform features low hydroxyl content and low sensitivity to hydrogen. Fibers drawn from the preform exhibit low attenuation losses from absorption by the broad band centered near 1380 nm.

First claim

We claim:

1 . A method of producing an optical fiber comprising:
providing a porous soot cladding monolith, said soot cladding monolith including a first porous glass cladding layer and having an internal cavity; inserting a core cane into said internal cavity to form a core-cladding assembly, said core-cladding assembly including a channel between said core cane and said soot cladding monolith; exposing said core-cladding assembly to a first gas atmosphere at a first temperature, said first gas atmosphere comprising a chlorine source material, said chlorine source material providing chlorine for doping said first porous glass cladding layer; exposing said core-cladding assembly to a second gas atmosphere at a second temperature, said second gas atmosphere comprising a reducing agent; and heating said core-cladding assembly in the presence of said second gas atmosphere at a third temperature, said heating causing sintering of said first porous glass cladding layer, said sintered first porous glass cladding layer having a chlorine dopant concentration of at least 500 ppm by weight.

2 . The method of claim 1 , wherein said first temperature is at least 800° C., said second temperature is greater than or equal to said first temperature, and said third temperature is greater than or equal to said second temperature.

3 . The method of claim 2 , wherein said first temperature is at least 1050° C.

4 . The method of claim 3 , wherein said third temperature is at least 1300° C.

5 . The method of claim 1 , wherein said chlorine source material is Cl 2 , SiCl 4 , or CCl 4 .

6 . The method of claim 1 , wherein said reducing agent is CO, CH 3 Cl, CH 2 Cl 2 , or CHCl 3 .

7 . The method of claim 1 , wherein said reducing agent is CO and the concentration of CO in said second gas atmosphere is greater than 3000 ppm by volume.

8 . The method of claim 1 , wherein said second gas atmosphere comprises said first gas atmosphere.

9 . The method of claim 8 , wherein the volumetric ratio of said reducing agent to said chlorine source material in said second gas atmosphere is greater than 0.010.

10 . The method of claim 1 , wherein said chlorine dopant concentration in said sintered first porous glass cladding layer is greater than 2000 ppm by weight.

11 . The method of claim 1 , wherein said soot cladding monolith further comprises a second porous glass cladding layer, said second porous glass cladding layer surrounding said first porous glass cladding layer.

12 . The method of claim 11 , wherein
said chlorine source material further provides chlorine for doping said second porous glass cladding layer and said heating at said third temperature causes sintering of said second porous glass cladding layer, said chlorine dopant concentration of said sintered first porous glass cladding layer being at least 1000 ppm by weight and said sintered second porous glass cladding layer having a chlorine dopant concentration less than said chlorine dopant concentration of said sintered first porous glass cladding layer.

13 . The method of claim 1 , further comprising drawing a fiber from said heated core-cladding assembly having said sintered first porous glass cladding layer.

14 . A method for forming an optical fiber preform comprising:
providing a soot cladding monolith, said soot cladding monolith including an internal cavity; inserting a core cane into said internal cavity to form a core-cladding assembly, said core-cladding assembly including said core cane and said soot cladding monolith; and heating said core-cladding assembly in the presence of a reducing agent.

15 . The method of claim 14 , wherein said providing soot cladding monolith includes forming said soot cladding monolith.

16 . The method of claim 15 , wherein said forming said soot cladding monolith includes reacting a soot precursor.

17 . The method of claim 16 , wherein said forming said soot cladding monolith includes depositing a first layer of soot formed from said reaction of said soot precursor on a substrate.

18 . The method of claim 17 , wherein said forming soot cladding monolith further includes forming said internal cavity, said forming internal cavity including separating said substrate from said first layer of soot.

19 . The method of claim 17 , wherein said forming said soot cladding monolith further includes depositing a second layer of soot on said first layer of soot.

20 . The method of claim 19 , wherein the density of said second layer of soot is greater than the density of said first layer of soot.

21 . The method of claim 14 , wherein said soot cladding monolith comprises silica.

22 . The method of claim 21 , wherein said soot cladding monolith further comprises a dopant.

23 . The method of claim 22 , wherein said dopant is chlorine.

24 . The method of claim 23 , wherein the concentration of said dopant in said soot cladding monolith is at least 2000 ppm by weight.

25 . The method of claim 14 , wherein said core cane comprises silica.

26 . The method of claim 14 , wherein said reducing agent includes CO.

27 . The method of claim 14 , wherein said heating said core-cladding assembly includes exposing said core-cladding assembly to a continuously flowing gas.

28 . The method of claim 27 , wherein said core-cladding assembly includes a flow pathway between said inserted core cane and said internal cavity, said continuously flowing gas entering said flow pathway.

29 . The method of claim 28 , wherein said continuously flowing gas includes a reducing agent.

30 . An optical fiber formed by drawing the optical fiber preform formed by the method of claim 14 .

Assignees

• Corning Inc

Inventors

• Billings Amanda Lee
• Bookbinder Dana Craig
• Desorcie Robert Brett
• De Paor Liam Ruan
• Tandon Pushkar
• Yang Li

Classifications

• G02B6/03627

  arranged - + · CPC title

• Y02P40/57

  Improving the yield, e-g- reduction of reject rates · CPC title

• C03B2203/23

  Double or multiple optical cladding profiles · CPC title

• C03B37/01248

  by collapsing without drawing · CPC title

• G02B6/021

  characterised by the core or cladding or coating, e.g. materials, radial refractive index profiles, cladding shape · CPC title