Optical fiber preform

Patent metadata

Field	Value
Publication number	US-10723650-B2
Application number	US-201816031319-A
Country	US
Kind code	B2
Filing date	Jul 10, 2018
Priority date	Jul 12, 2017
Publication date	Jul 28, 2020
Grant date	Jul 28, 2020

Abstract

An optical fiber preform includes a silica-glass core portion, and a cladding portion surrounding the core portion, the cladding portion being composed of a fluorine-containing silica glass having a lower refractive index than the core portion, the core portion including a first region that does not include the central axis thereof, the first region containing a first dopant selected from sodium, potassium, and compounds thereof, and a second region that includes the central axis, the second region containing a second dopant that reduces the viscosity of the silica glass, the second dopant having a diffusion coefficient of 1×10−12 cm2/s or more and less than the first dopant at 2,000° C. to 2,300° C., in which the entire core portion has an average first dopant concentration of 10 atomic ppm or more and 2,000 atomic ppm or less and an average second dopant concentration of 10 atomic ppm or more.

First claim

What is claimed is:

1. An optical fiber preform comprising:
a core portion composed of a silica glass; and
a cladding portion surrounding the core portion, the cladding portion being composed of a fluorine-containing silica glass having a lower refractive index than the core portion, the core portion including:
a first region that does not include a central axis of the core portion, the first region containing a first dopant selected from sodium, potassium, and compounds thereof, and
a second region that includes the central axis of the core portion, the second region containing a second dopant that reduces viscosity of the silica glass, the second dopant having a diffusion coefficient of 1×10 −12 cm 2 /s or more and less than the first dopant at a temperature of 2,000° C. to 2,300° C.,

wherein the first dopant has a peak concentration at a radius r 1 in the core portion and the core portion has an outer radius r 2 and a ratio (r 2 /r 1 ) is in the range of 3 to 9.5,
the entire core portion has an average first dopant concentration of 10 atomic ppm or more and 2,000 atomic ppm or less, and
the entire core portion has an average second dopant concentration of 10 atomic ppm or more.

2. The optical fiber preform according to claim 1 , wherein
the second dopant is any one selected from Rb, Cs, Mg, Ca, and Sr.

3. The optical fiber preform according to claim 1 , wherein
the entire core portion has an average Cl concentration of 10 atomic ppm or more and 10,000 atomic ppm or less.

4. The optical fiber preform according to claim 2 , wherein
the entire core portion has an average Cl concentration of 10 atomic ppm or more and 10,000 atomic ppm or less.

5. An optical fiber preform comprising:
a core portion composed of a silica glass; and
a cladding portion surrounding the core portion, the cladding portion being composed of a fluorine-containing silica glass having a lower refractive index than the core portion, the core portion including:
a first region that does not include a central axis of the core portion, the first region containing a first dopant selected from sodium, potassium, and compounds thereof, and
a second region that includes the central axis of the core portion, the second region containing a second dopant that reduces viscosity of the silica glass, the second dopant having a diffusion coefficient of 1×10 −12 cm 2 /s or more and less than the first dopant at a temperature of 2,000° C. to 2,300° C.,
wherein the first dopant has a peak concentration at a radius r 1 in the core portion, the radius r 1 being larger than a radius at which the second dopant has a peak concentration,
the entire core portion has an average first dopant concentration of 10 atomic ppm or more and 2,000 atomic ppm or less, and
the entire core portion has an average second dopant concentration of 10 atomic ppm or more.

6. The optical fiber preform according to claim 5 , wherein the second dopant is any one selected from Rb, Cs, Mg, Ca, and Sr.

7. The optical fiber preform according to claim 5 , wherein
the core portion has an outer radius r 2 , and a ratio (r 2 /r 1 ) is in the range of 3 to 9.5.

8. The optical fiber preform according to claim 5 , wherein
the entire core portion has an average Cl concentration of 10 atomic ppm or more and 10,000 atomic ppm or less.

9. The optical fiber preform according to claim 6 , wherein
the entire core portion has an average Cl concentration of 10 atomic ppm or more and 10,000 atomic ppm or less.

10. The optical fiber preform according to claim 7 , wherein
the entire core portion has an average Cl concentration of 10 atomic ppm or more and 10,000 atomic ppm or less.

Assignees

• Sumitomo Electric Industries

Inventors

• Morita Keisei
• Tamura Yoshiaki
• Sakuma Hirotaka

Classifications

• C03C3/06 Primary

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

• C03B2203/29

  Segmented core fibres · CPC title

• C03B2201/54

  doped with beryllium, magnesium or alkaline earth metals · CPC title

• C03B37/01228

  Removal of preform material (C03B37/01251 takes precedence) · CPC title

• C03B37/01248

  by collapsing without drawing · CPC title