Optical fiber

Patent metadata

Field	Value
Publication number	US-10670812-B2
Application number	US-201716329145-A
Country	US
Kind code	B2
Filing date	May 30, 2017
Priority date	Aug 30, 2016
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

An optical fiber includes: a core that includes quartz glass doped with a core updopant; an inner cladding that includes quartz glass doped with a cladding updopant and a downdopant and that covers a circumferential surface of the core; and an outer cladding that includes quartz glass and that covers an outer circumferential surface of the inner cladding. A refractive index of the inner cladding is substantially equal to a refractive index of the outer cladding. The inner cladding contains the cladding updopant at a concentration such that a refractive index increase rate ascribed to the cladding updopant falls within a range of 0.25% to 0.5%.

First claim

The invention claimed is:

1. An optical fiber comprising:
a core that comprises quartz glass doped with a core updopant;
an inner cladding that comprises quartz glass doped with a cladding updopant and a downdopant and that covers a circumferential surface of the core; and
an outer cladding that comprises quartz glass and that covers an outer circumferential surface of the inner cladding, wherein
a refractive index of the inner cladding is substantially equal to a refractive index of the outer cladding, and
the inner cladding contains the cladding updopant at a concentration such that a refractive index increase rate ascribed to the cladding updopant falls within a range of 0.25% to 0.5%.

2. The optical fiber according to claim 1 , wherein the core contains the core updopant at a concentration such that a mode field diameter at a wavelength of 1550 nm falls within a range of 3.5 μm to 6.5 μm.

3. The optical fiber according to claim 1 , wherein the inner cladding contains the downdopant at a concentration such that an absolute value of a relative refractive index difference of the inner cladding with respect to the outer cladding is 0.1% or less.

4. The optical fiber according to claim 1 , wherein
the core is doped with germanium as the core updopant, and
the inner cladding is doped with fluorine as the downdopant.

5. The optical fiber according to claim 4 , wherein the inner cladding is doped with one or both of phosphorus and germanium as the cladding updopant.

6. The optical fiber according to claim 4 , wherein the inner cladding is further doped with boron as the downdopant.

7. The optical fiber according to claim 1 , further comprising a pair of stress applying sections disposed symmetrically with respect to the core.

8. The optical fiber according to claim 7 , wherein the pair of stress applying sections are disposed such that respective outer edges of the stress applying sections are in contact with or apart from an outer edge of the inner cladding.

9. An optical device comprising:
the optical fiber according to claim 1 ;
a semiconductor optical waveguide butt-joined to one end of the optical fiber; and
a conventional single mode fiber (CSMF) that is fusion-spliced to an other end of the optical fiber.

10. The optical fiber as set forth in claim 1 , wherein the optical fiber is fusion-spliced to a conventional single mode fiber (CSMF).

11. The optical fiber according to claim 1 , wherein, in at least one end of the optical fiber during heat treatment or after the heat treatment, the outer cladding includes a first region with a relative refractive index difference lower than that of the inner cladding and an outer side of the first region includes a second region with a relative refractive index difference that is higher than that of the first region.

12. The optical fiber according to claim 1 , wherein, in at least one end of the optical fiber during heat treatment or after the heat treatment, the core includes at least one region in which a concentration of the downdopant is greater than zero.

13. The optical fiber according to claim 11 , wherein, in the at least one end of the optical fiber after the heat treatment, the concentration of the downdopant inside an entirety of the core is greater than zero.

14. An optical device comprising:
the optical fiber according to claim 1 ; and
a conventional single mode fiber (CSMF) fusion-spliced to one end of the optical fiber.

15. The optical device according to claim 14 , further comprising:
a semiconductor optical waveguide that is butt-joined to an other end of the optical fiber.

16. The optical fiber according to claim 10 , wherein the CSMF is a G.652 or G.657 classified optical fiber defined by ITU Telecommunication Standardization Sector (ITU-T) standards.

Assignees

• Fujikura Ltd

Inventors

• Hirakawa Keisuke
• Ichii Kentaro
• Hayashi Kazuyuki

Classifications

• G02B6/036

  core or cladding comprising multiple layers {(multicore optical fibres G02B6/02042; microstructured properties G02B6/02295; omniguide fibres G02B6/023)} · CPC title

• G02B6/30 Primary

  for use between fibre and thin-film device · CPC title

• G02B6/255

  Splicing of light guides, e.g. by fusion or bonding · CPC title

• G02B6/024

  with polarisation maintaining properties · CPC title

• G02B6/03694 Primary

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