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

Patent metadata

Field	Value
Publication number	US-9772445-B2
Application number	US-201615091852-A
Country	US
Kind code	B2
Filing date	Apr 6, 2016
Priority date	Apr 7, 2015
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

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 1 MAX ;
an inner cladding surrounding the core and having a minimum relative refractive index Δ 2 such that Δ 1 MAX >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: (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.

Assignees

• Corning Inc

Inventors

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

Classifications

• G02B6/03694 Primary

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

• G02B6/03644

  arranged - + - · CPC title

• G02B6/03627

  arranged - + · CPC title

• G02B6/0281

  Graded index region forming part of the central core segment, e.g. alpha profile, triangular, trapezoidal core (G02B6/0288, G02B6/0286 take precedence) · CPC title

• G02B6/02395

  Glass optical fibre with a protective coating, e.g. two layer polymer coating deposited directly on a silica cladding surface during fibre manufacture (G02B6/02052, G02B6/02057, G02B6/024, G02B6/032, G02B6/105, G02B6/14 take precedence; coating on fibre gratings G02B6/02104; multilayer core or cladding G02B6/036; reinforcing splice joints G02B6/2558; optical cables, i.e. comprising protective structures external to the protective coating such as a jacket or plural coated optical fibres G02B6/44; coating of glass to obtain optical fibres C03C25/104) · CPC title