Amplification optical fiber, fiber laser device, and optical resonator

Patent metadata

Field	Value
Publication number	US-11095086-B2
Application number	US-201816208142-A
Country	US
Kind code	B2
Filing date	Dec 3, 2018
Priority date	Mar 30, 2018
Publication date	Aug 17, 2021
Grant date	Aug 17, 2021

Abstract

An amplification optical fiber includes: a core; an inner cladding having a refractive index lower than a refractive index of the core, wherein an active element pumped by pumping light is entirely doped to the core, and a relative effective refractive index difference of light in an LP01 mode is greater than or equal to 0.05% and a relative effective refractive index difference of light in an LP21 mode is less than 0.05% in light propagating through the core.

First claim

The invention claimed is:

1. An amplification optical fiber comprising:
a core;
a cladding having a refractive index lower than a refractive index of the core, wherein
an active element pumped by pumping light is entirely doped to the core, and
a relative effective refractive index difference of light in an LP01 mode is greater than or equal to 0.05% and a relative effective refractive index difference of light in an LP21 mode is less than 0.05% in light propagating through the core.

2. The amplification optical fiber according to claim 1 , wherein a relative effective refractive index difference of light in an LP11 mode is less than 0.05% in light propagating through the core.

3. The amplification optical fiber according to claim 1 , wherein a relative effective refractive index difference of light in an LP11 mode is greater than or equal to 0.05% in light propagating through the core.

4. The amplification optical fiber according to claim 1 , wherein a refractive index profile of the core corresponds to a concentration profile of the active element.

5. The amplification optical fiber according to claim 1 , wherein an effective area of light in the LP01 mode propagating through the core is greater than or equal to 200 μm 2 .

6. The amplification optical fiber according to claim 5 , wherein the effective area of light in the LP01 mode propagating through the core is less than or equal to 400 μm 2 .

7. The amplification optical fiber according to claim 1 , wherein a relative refractive index difference of the core is greater than or equal to 0.08%.

8. The amplification optical fiber according to claim 1 , wherein the active element is ytterbium.

9. The amplification optical fiber according to claim 1 , wherein a diameter of the core is greater than or equal to 23 μm and less than or equal to 27 μm.

10. A fiber laser device comprising:
the amplification optical fiber according to claim 1 ; and
a pumping light source that emits the pumping light that enters the amplification optical fiber.

11. An optical resonator comprising:
the amplification optical fiber according to claim 1 ;
a first mirror that is optically coupled to the core of the amplification optical fiber on one side of the amplification optical fiber and reflects at least part of light having wavelengths emitted by the active element in a pumped state; and
a second mirror that is optically coupled to the core of the amplification optical fiber on the opposite side of the amplification optical fiber and reflects at least part of light having wavelengths reflected by the first mirror with a reflectivity lower than a reflectivity of the first mirror.

Assignees

• Fujikura Ltd

Inventors

• Kitahara Rintaro
• Miyauchi Hidenori

Classifications

• 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

• H01S3/0672

  Non-uniform radial doping · CPC title

• H01S3/06716 Primary

  Fibre compositions (per se C03C13/04)or doping with active elements (lasing materials in general H01S3/14) · CPC title

• H01S3/09415

  the pumping beam being parallel to the lasing mode of the pumped medium, e.g. end-pumping · CPC title

• H01S3/08045

  Single-mode emission · CPC title