Optical fiber assembly for mitigating stimulated Brillouin scattering

Patent metadata

Field	Value
Publication number	US-12407144-B2
Application number	US-202217837124-A
Country	US
Kind code	B2
Filing date	Jun 10, 2022
Priority date	Jun 10, 2022
Publication date	Sep 2, 2025
Grant date	Sep 2, 2025

Abstract

An optical fiber assembly for mitigating stimulated Brillouin scattering (SBS) is disclosed that includes an optical fiber and a winding support configured to hold the fiber in a winding arrangement. The fiber includes a core and one or more claddings surrounding the core. The one or more claddings includes an inner doped region contiguous to the core and having a composition including a glass material doped with an acoustic-velocity-lowering and refractive-index-raising dopant and an acoustic-velocity-lowering and refractive-index-lowering dopant. The composition is selected to provide the fiber with an acoustic velocity profile in which the velocity within the inner doped region is equal to or less by at most 0.5% than that within the core. The acoustic velocity profile and the winding arrangement provide SBS mitigation by reducing a mode overlap between an optical mode guided in the core and acoustic modes including guided and leaky acoustic modes.

First claim

The invention claimed is:

1. An optical fiber assembly for mitigating stimulated Brillouin scattering (SBS), the optical fiber assembly comprising:
an optical fiber comprising:
a core extending along a longitudinal fiber axis; and
one or more claddings surrounding the core and extending along the longitudinal fiber axis, an innermost one of the one or more claddings having a refractive index that is lower than a refractive index of the core, the one or more claddings comprising an inner doped region contiguous to the core, the inner doped region having a composition comprising a cladding glass material doped with at least one acoustic-velocity-lowering and refractive-index-raising dopant and at least one acoustic-velocity-lowering and refractive-index-lowering dopant, the composition of the inner doped region being selected to provide the optical fiber with a radial acoustic velocity profile in which a longitudinal acoustic velocity within the inner doped region is equal to or less by at most 0.5% than a longitudinal acoustic velocity within the core; and

a winding support configured to hold the optical fiber in a winding arrangement,
wherein the radial acoustic velocity profile and the winding arrangement of the optical fiber provide SBS mitigation by reducing a mode overlap between an optical mode guided in the core and acoustic modes comprising a guided acoustic mode and a leaky acoustic mode.

2. The optical fiber assembly of claim 1 , wherein the cladding glass material is silica glass, the at least one acoustic-velocity-lowering and refractive-index-raising dopant comprises germanium oxide, phosphorus oxide, or any combination thereof, and the at least one acoustic-velocity-lowering and refractive-index-lowering dopant comprises boron oxide, fluorine, or any combination thereof.

3. The optical fiber assembly of claim 2 , wherein the at least one acoustic-velocity-lowering and refractive-index-raising dopant comprises germanium oxide with a concentration ranging from about 0.1 mol % to about 15.0 mol %, and the at least one acoustic-velocity-lowering and refractive-index-lowering dopant comprises fluorine with a concentration ranging from about 0.1 mol % to about 5.0 mol %.

4. The optical fiber assembly of claim 1 , wherein a ratio of an outer diameter of the inner doped region to an inner diameter of the inner doped region ranges from about 1.1 to about 20.

5. The optical fiber assembly of claim 1 , wherein the inner doped region extends within the innermost cladding between the core and an outer undoped region of the innermost cladding, and wherein the composition of the inner doped region is selected to provide the inner doped region with a refractive index that matches a refractive index of the outer undoped region.

6. The optical fiber assembly of claim 5 , wherein the outer undoped region is made of silica glass.

7. The optical fiber assembly of claim 1 , wherein the one or more claddings comprise an additional doped region contiguously surrounding the inner doped region, and wherein a composition of the additional doped region is selected to make a longitudinal acoustic velocity within the additional doped region lower than the longitudinal acoustic velocity within the inner doped region.

8. The optical fiber assembly of claim 7 , wherein the additional doped region extends within the innermost cladding.

9. The optical fiber assembly of claim 1 , wherein the one or more claddings comprise a plurality of claddings having different refractive indices, and wherein the inner doped region extends through the entirety of the innermost cladding.

10. The optical fiber assembly of claim 1 , wherein the one or more claddings comprise an outer cladding contiguously surrounding the innermost cladding, the outer cladding having a refractive index that is lower than the refractive index of the innermost cladding for guiding pump light inside the innermost cladding.

11. The optical fiber assembly of claim 1 , wherein the core is composed of a core glass material doped with at least one core dopant.

12. The optical fiber assembly of claim 11 , wherein the core glass material is silica glass, and the at least one core dopant comprises germanium oxide, aluminum oxide, phosphorus oxide, fluorine, a rare-earth oxide, or any combination thereof.

13. The optical fiber assembly of claim 1 , wherein the core comprises a central region having a central core composition and a peripheral region surrounding the central region and having a peripheral core composition, and wherein the central core composition and the peripheral core composition are selected to make the longitudinal acoustic velocity within the core higher in the central region than in the peripheral region.

14. The optical fiber assembly of claim 1 , wherein the core has an outer diameter ranging from about 10 μm to about 60 μm.

15. The optical fiber assembly of claim 1 , wherein the winding arrangement has an average winding radius ranging from about 3 cm to about 40 cm.

16. The optical fiber assembly of claim 1 , wherein the optical fiber is a polarization-maintaining fiber and comprises at least one stress-applying part disposed within the one or more claddings and extending along the longitudinal fiber axis.

17. The optical fiber assembly of claim 16 , wherein the at least one stress-applying part extends at least partly within the inner doped region.

18. An optical fiber having reduced stimulated Brillouin scattering (SBS), the optical fiber comprising:
a core extending along a longitudinal fiber axis; and
one or more claddings surrounding the core and extending along the longitudinal fiber axis, an innermost one of the one or more claddings having a refractive index that is lower than a refractive index of the core, the one or more claddings comprising an inner doped region contiguous to the core, the inner doped region having a composition comprising a cladding glass material doped with at least one acoustic-velocity-lowering and refractive-index-raising dopant and at least one acoustic-velocity-lowering and refractive-index-lowering dopant, the composition of the inner doped region being selected to provide the optical fiber with a radial acoustic velocity profile in which a longitudinal acoustic velocity within the inner doped region is equal to or less by at most 0.5% than a longitudinal acoustic velocity within the core,
wherein the optical fiber is configured to be wound in a winding arrangement onto a winding support, and
wherein the radial acoustic velocity profile and the winding arrangement of the optical fiber provide SBS mitigation by reducing a mode overlap between an optical mode guided in the core and acoustic modes comprising a guided acoustic mode and a leaky acoustic mode.

Assignees

• Institut Nat Doptique

Inventors

• Boivin Mathieu

Classifications

• H01S3/06733 Primary

  Fibre having more than one cladding · CPC title

• H01S2301/03

  Suppression of nonlinear conversion, e.g. specific design to suppress for example stimulated brillouin scattering [SBS], mainly in optical fibres in combination with multimode pumping · CPC title

• H01S3/1691

  characterised by additives / sensitisers / promoters as further dopants · CPC title

• H01S3/1616

  thulium · CPC title

• H01S3/1608

  erbium · CPC title