Ytterbium-doped optical fiber, fiber laser and fiber amplifier

• US 8,941,912 B2
• Filed: 02/03/2011
• Issued: 01/27/2015
• Est. Priority Date: 08/04/2008
• Status: Active Grant

• Current Assignee: Fujikura Limited
• Original Assignee: Fujikura Limited
• Inventors: Tanigawa, Shoji, Nakaguma, Teruno, Arai, Tomofumi, Ichii, Kentaro
• Primary Examiner(s): BOLDA, ERIC L
• Application Number:
  US13/020,604
• Publication Number:
  US 20110142083A1
• Time in Patent Office: 1,454 Days
• Field of Search: 359/341.1, 359/341.5, 385/123, 385/126, 385/127
• US Class Current: 359/341.5
• CPC Class Codes: C03C 13/046 Multicomponent glass compositions
• CPC Class Codes: G02B 6/02 Optical fibres with cladding with or without a coating
• CPC Class Codes: G02B 6/02395 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 Class Codes: G02B 6/024 with polarisation maintaining properties
• CPC Class Codes: G02B 6/0285 Graded index layer adjacent to the central core segment and ending at the outer cladding index
• CPC Class Codes: G02B 6/03611 Highest index adjacent to central axis region, e.g. annular core, coaxial ring, centreline depression affecting waveguiding
• CPC Class Codes: G02B 6/03633 arranged - -
• CPC Class Codes: G02B 6/03638 having 3 layers only
• CPC Class Codes: G02B 6/03644 arranged - + -
• CPC Class Codes: G02B 6/0365 arranged - - +
• CPC Class Codes: G02B 6/03661 having 4 layers only
• CPC Class Codes: H01S 3/06708 Constructional details of the fibre, e.g. compositions, cross-section, shape or tapering optical fibres as passive waveguides G02B6/02
• CPC Class Codes: H01S 3/06716 Fibre compositions per se C03C13/04or doping with active elements lasing materials in general H01S3/14
• CPC Class Codes: H01S 3/0672 Non-uniform radial doping
• CPC Class Codes: H01S 3/06729 Peculiar transverse fibre profile
• CPC Class Codes: H01S 3/06737 Fibre having multiple non-coaxial cores, e.g. multiple active cores or separate cores for pump and gain
• CPC Class Codes: H01S 3/1618 ytterbium
• CPC Class Codes: H01S 3/1691 characterised by additives / sensitisers / promoters as further dopants
• CPC Class Codes: H01S 3/1693 aluminium

Abstract

An ytterbium-doped optical fiber includes: a core which contains at least ytterbium, aluminum, and phosphorus; and a cladding which encircles the core, wherein an aluminum oxide equivalent concentration of the aluminum in the core is 0.2 mol % or more, a diphosphorus pentaoxide equivalent concentration of the phosphorus is higher than the aluminum oxide equivalent concentration, and the core either does not contain germanium or contains less than 1.1 mol % of germanium in a germanium dioxide equivalent concentration.

Claims

1. An ytterbium-doped optical fiber comprising:

a core which consists of ytterbium, aluminum, phosphorus, fluorine, and at least one element selected from a group consisting of transition metal elements and rare earth elements other than ytterbium and erbium; and

a cladding which encircles the core, wherein

an aluminum oxide equivalent concentration of the aluminum in the core is 0.2 mol % or more;

a diphosphorus pentaoxide equivalent concentration of the phosphorus is higher than the aluminum oxide equivalent concentration; and

the core either does not contain germanium or contains less than 1.1 mol % of germanium in a germanium dioxide equivalent concentration,

wherein the diphosphorous pentaoxide equivalent concentration in the core is greater than a summation of an ytterbium oxide equivalent concentration of the ytterbium and the aluminum oxide equivalent concentration in the core, and the ytterbium oxide equivalent concentration in the core is in a range of 0.01 to 1.0 mol %.

2. The ytterbium-doped optical fiber according to claim 1, wherein

the core and the cladding are formed from silica glass.

3. The ytterbium-doped optical fiber according to claim 1, wherein

a ratio between an ytterbium oxide equivalent concentration and the aluminum oxide equivalent concentration in the core is in a range of 0.01 to 2.

4. The ytterbium-doped optical fiber according to claim 1, wherein

the diphosphorus pentaoxide equivalent concentration in the core is 20 mol % or less.

5. The ytterbium-doped optical fiber according to claim 1, wherein

the diphosphorus pentaoxide equivalent concentration is not more than twice the aluminum oxide equivalent concentration in the core.

6. The ytterbium-doped optical fiber according to claim 1, wherein

a relative refractive index difference between the core and the cladding is in a range of 0.05 to 0.65%.

7. The ytterbium-doped optical fiber according to claim 6, wherein

the relative refractive index difference between the core and the cladding is in a range of 0.05 to 0.25%.

8. The ytterbium-doped optical fiber according to claim 1, wherein

the core further contains fluorine.

9. The ytterbium-doped optical fiber according to claim 1, wherein

the core further contains at least one element selected from a group consists of transition metal elements other than ytterbium.

10. The ytterbium-doped optical fiber according to claim 1, wherein

at least two layers of cladding are provided;

and

a refractive index of the cladding on an inner side in a radial direction is higher than a refractive index of the cladding on an outer side in the radial direction.

11. The ytterbium-doped optical fiber according to claim 10, wherein

at least three layers of cladding are provided;

and

a refractive index nc1 of the cladding on an innermost side in the radial direction, a refractive index nc3 of the cladding on an outermost side in the radial direction, and a refractive index nc2 of an intermediate cladding between the innermost cladding and the outermost cladding satisfy a relationship of nc1>

nc2>

nc3.

12. A fiber laser comprising the ytterbium-doped optical fiber according to claim 1 as an optical amplifying medium.

13. A fiber amplifier comprising the ytterbium-doped optical fiber according to claim 1 as an optical amplifying medium.