Low attenuation fiber with stress relieving layer and a method of making such

Patent metadata

Field	Value
Publication number	US-2016299289-A1
Application number	US-201615091852-A
Country	US
Kind code	A1
Filing date	Apr 6, 2016
Priority date	Apr 7, 2015
Publication date	Oct 13, 2016
Grant date	—

Abstract

A single mode optical fiber having a core made from silica and less than or equal to about 11 weight % germania and having a maximum relative refractive index Δ 1MAX . The optical fiber also has an inner cladding surrounding the core and having a minimum relative refractive index Δ 2MIN , a first outer cladding surrounding the inner cladding and a second outer cladding surrounding the first outer cladding. The viscosity at 1650° C. of the second outer cladding minus the viscosity at 1650° C. of the first outer cladding is greater than 0.1e 7 Poise, and Δ 1MAX >Δ 2MIN . The single mode optical fiber may also have an outer cladding surrounding the inner cladding made from silica or SiON. The first outer cladding has a maximum relative refractive index Δ 3MAX , and Δ 3MAX >Δ 2MIN .

First claim

What is claimed is:

1 . A single mode optical fiber comprising:
a core comprising silica and less than or equal to about 11 weight % germania and having a maximum relative refractive index Δ 1MAX ; an inner cladding surrounding the core and having a minimum relative refractive index Δ 2 such that Δ 1MAX >Δ 2 ; an outer cladding surrounding the inner cladding and comprising a first outer cladding portion and a second outer cladding portion surrounding the first outer cladding portion; wherein the viscosity at 1650° C. of the second outer cladding portion minus the viscosity at 1650° C. of the first outer cladding portion is ≧1×10 6 Poise. The single mode optical fiber of claim 1 , wherein the viscosity at 1650° C. of the second outer cladding portion minus the viscosity at 1650° C. of the first outer cladding portion is: (i) ≧5×10 6 Poise; or (ii) ≧1×10 6 Poise and ≦1.6×10 8 Poise.

2 . The single mode optical fiber of claim 1 , wherein the first outer cladding portion has a softening point, T soft-1 , and the second outer cladding portion has a softening point, T soft-2 ; and
the difference between the glass softening point of the second outer cladding portion, T soft-2 , and the glass softening point of the first cladding outer cladding portion, T soft-1 , is greater than 2° C.

3 . The single mode optical fiber of claim 1 , where the first outer cladding portion has a softening point, T soft-1 , and the second outer cladding portion has a softening point, T soft-2 ; and the difference between the glass softening point of the second outer cladding portion, T soft-2 , and the glass softening point of the first cladding outer cladding portion, T soft-1 , is greater than 7° C.

4 . The single mode optical fiber of claim 1 , wherein at least one of the following is satisfied: (i) the core comprises from greater than or equal to about 2.0 weight % germania; or (ii) the core has a maximum relative refractive index, Δ 1MAX , from greater than or equal to about 0.13% to less than or equal to about 0.52%; or (iii) −0.02%≦Δ 2 ≦0.02%.

5 . The single mode optical fiber of claim 1 , wherein the core has a radial thickness from greater than or equal to about 3 microns to less than or equal to about 10 microns.

6 . The single mode optical fiber of claim 5 , wherein the inner cladding has a radial thickness from greater than or equal to about 5 microns.

7 . The single mode optical fiber of claim 1 , wherein the first outer cladding portion surrounds the inner cladding,
the first outer cladding portion comprises chlorine doped silica, the first outer cladding portion has a relative refractive index Δ 3A , and Δ 3A >Δ 2 .

8 . The single mode optical fiber of claim 1 , wherein the second outer cladding portion is surrounding the first outer cladding portion,
the first outer cladding portion comprises chlorine doped silica and has a relative refractive index Δ 3A , the second outer cladding portion comprises chlorine doped silica, silica or SiON, and Δ 3A >Δ 2 .

9 . The single mode fiber of claim 1 , wherein the core comprises from greater than or equal to about 2.0 weight % germania, and wherein:
(i) the second outer cladding portion comprises at least 1000 ppm by weight less chlorine than the first outer cladding portion; or (ii) the first outer cladding portion has an average chlorine concentration between 2000-20000 ppm by weight; or (iii) the second outer cladding portion has a chlorine concentration between 0-6000 ppm by weight, and wherein the second outer cladding portion comprises at least 1000 ppm by weight less chlorine than the first outer cladding portion

10 . The single mode optical fiber of claim 1 , wherein the core comprises from greater than or equal to about 2.0 weight % germania and the second outer cladding portion has a radial thickness from greater than or equal to about 2 microns to less than or equal to about 25 microns.

11 . The single mode optical fiber of claim 1 , wherein the single mode optical fiber has an attenuation of less than or equal to about 0.185 dB/km at a wavelength of 1550 nm.

12 . The single mode optical fiber of claim 1 , having a normalized stress relieving parameter Φ, where Φ≧5.

13 . The single mode optical fiber of claim 1 , having a normalized stress relieving parameter Φ, where 100≧Φ≧5.

14 . The single mode optical fiber of claim 1 , wherein the second outer cladding portion is in tension, the tension producing an axial stress of greater than 0.3 MPa, and preferably greater than 2 MPa.

15 . An optical fiber preform comprising:
(i) a core comprising silica and less than or equal to about 11 weight % germania and having a maximum relative refractive index Δ 1MAX ; (ii) an inner clad surrounding the core and having a minimum relative refractive index Δ 2 such that Δ 1MAX >Δ 2 ; and (iii) an outer clad surrounding the inner clad and comprising a first outer clad portion and a second outer clad portion surrounding the first outer clad portion; and
wherein the viscosity (at 1650° C.) of the second outer clad portion minus the viscosity (at 1650° C.) of the first outer clad portion is ≧1×10 6 Poise.

16 . The optical fiber preform of claim 15 , wherein the viscosity at 1650° C. of the second outer clad portion minus the viscosity at 1650° C. of the first outer clad portion is ≧5×10 6 Poise.

17 . The optical fiber preform of claim 15 , wherein the viscosity at 1650° C. of the second outer clad portion minus the viscosity at 1650° C. of the first outer clad portion is ≧1×10 6 Poise and ≦1.6×10 8 Poise.

18 . The optical fiber preform of claim 15 , wherein the first outer clad portion has a softening point, T soft-1 , and the second outer clad portion has a softening point, T soft-2 ; and
the difference between the glass softening point of the second outer clad portion, T soft-2 , and the glass softening point of the first outer cladportion, T soft-1 , is greater than 2° C.

19 . The optical fiber preform of claim 18 , where the first outer clad portion has a softening point, T soft-1 , and the second outer clad portion has a softening point, T soft-2 ; and
the difference between the glass softening point of the second outer clad portion, T soft-2 , and the glass softening point of the first outer clad portion, T soft-1 s greater than 3° C.

20 . The optical fiber preform of claim 18 , where the first outer clad portion has a softening point, T soft-1 , and the second outer clad portion has a softening point, T soft-2 ; and
the difference between the glass softening point of the second outer clad portion, T soft-2 , and the glass softening point of the first outer clad portion, T soft-1 , is greater than 7° C.

21 . The optical fiber preform of claim 15 , wherein: (i) the second outer clad portion comprises at least 1000 ppm by weight less chlorine than the first outer clad portion; or (ii) the first outer clad portion has an average chlorine concentration between 2000-20000 ppm by weight; or (iii) wherein the second outer clad portion has a chlorine concentration between 0-6000 ppm by weight, and wherein the second outer clad portion comprises at least 1000 ppm by weight less chlorine than the first outer clad portion.

22 . A method of drawing an optical fiber comprising:
(i) providing an optical fiber preform comprising: (a) a core comprising silica and less than or equal to about 11 weight % germania and having a maximum relative refractive index Δ 1MAX ; (b) an inner clad surround

Assignees

• Corning Inc

Inventors

• Bookbinder Dana Craig
• Li Ming-Jun
• Tandon Pushkar

Classifications

• C03C3/06

  with more than 90% silica by weight, e.g. quartz {(C03C3/045 takes precedence)} · CPC title

• G02B6/03627

  arranged - + · CPC title

• C03B2203/222

  Mismatching viscosities or softening points of glass layers · CPC title

• G02B6/03694 Primary

  Multiple layers differing in properties other than the refractive index, e.g. attenuation, diffusion, stress properties · CPC title

• C03B37/027

  Fibres composed of different sorts of glass, {e.g. glass optical fibres}(C03B37/0253, C03B37/028 take precedence) · CPC title