Optical fiber for a fiber laser, fiber laser, and production method for optical fiber for a fiber laser

Patent metadata

Field	Value
Publication number	US-2022037847-A1
Application number	US-202117506936-A
Country	US
Kind code	A1
Filing date	Oct 21, 2021
Priority date	Oct 30, 2018
Publication date	Feb 3, 2022
Grant date	—

Abstract

An optical fiber for a fiber laser includes a core to which a rare-earth element is added, a first cladding formed around the core; and a second cladding formed around the first cladding, and excitation light is guided from at least one end of the first cladding to excite the rare-earth element to output a laser oscillation light. An addition concentration of the rare-earth element to the core is different in a longitudinal direction of the optical fiber for a fiber laser, and a core diameter and a numerical aperture of the optical fiber for a fiber laser are constant in the longitudinal direction of the optical fiber for a fiber laser.

First claim

What is claimed is:

1 . A production method for an optical fiber for a fiber laser including a core to which a rare-earth element is added, a first cladding formed around the core, and a second cladding formed around the first cladding, in which excitation light is guided from at least one end of the first cladding to excite the rare-earth element to output a laser oscillation light, wherein an addition concentration of the rare-earth element to the core is different in a longitudinal direction of the optical fiber for a fiber laser, and a core diameter and a numerical aperture of the optical fiber for a fiber laser are constant in the longitudinal direction of the optical fiber for a fiber laser, comprising:
stacking a plurality of disks formed of silica glass in which the addition concentration of the rare-earth element is changed in a thickness direction on an inner side of a hollow silica glass tube; fusing the tube and the plurality of disks together by heating to manufacture a preform; and performing wire drawing while heating the preform.

2 . A production method for an optical fiber for a fiber laser including a core to which a rare-earth element is added, a first cladding formed around the core, and a second cladding formed around the first cladding, in which excitation light is guided from at least one end of the first cladding to excite the rare-earth element to output a laser oscillation light, wherein an addition concentration of the rare-earth element to the core is different in a longitudinal direction of the optical fiber for a fiber laser, and a core diameter and a numerical aperture of the optical fiber for a fiber laser are constant in the longitudinal direction of the optical fiber for a fiber laser, comprising:
allowing a soot to grow while periodically changing the addition concentration of the rare-earth element in an axial direction by a vapor phase axial deposition method to manufacture a soot body; subjecting the soot body to silica vitrification to manufacture a rod; disposing the rod on an inner side of a hollow silica glass tube to manufacture a rod-in-tube; allowing the rod-in-tube to collapse to manufacture a preform; and performing wire drawing while heating the preform.

3 . The production method for the optical fiber for a fiber laser according to claim 2 , wherein
a manufacturing device for manufacturing the soot body includes a plurality of burners for depositing the soot by an oxyhydrogen flame hydrolysis method of a silicon tetrachloride and a surface shape monitoring device that monitors a surface shape of a soot deposition surface, and a monitoring result obtained by the surface shape monitoring device is provided as a feedback and the soot is deposited while adjusting heating power of the burners so that the surface shape of the soot deposition surface is kept to be a flat surface vertical to a central axis of the soot body.

4 . A production method for an optical fiber for a fiber laser including a core to which a rare-earth element is added, a first cladding formed around the core, and a second cladding formed around the first cladding, in which excitation light is guided from at least one end of the first cladding to excite the rare-earth element to output a laser oscillation light, wherein an addition concentration of the rare-earth element to the core is different in a longitudinal direction of the optical fiber for a fiber laser, and a core diameter and a numerical aperture of the optical fiber for a fiber laser are constant in the longitudinal direction of the optical fiber for a fiber laser, comprising:
supplying raw gas to an inner side of a hollow silica glass tube to deposit silica glass by a plasma activated chemical vapor deposition method while changing the concentration of the rare-earth element periodically according to movement in the longitudinal direction of the tube, of a deposition position of silica glass where a high-frequency induction thermal plasma is generated in the tube, allowing the tube to collapse to manufacture a preform; and performing wire drawing while heating the preform.

Assignees

• Fanuc Corp

Inventors

• Takigawa Hiroshi
• Takazane Tetsuhisa

Classifications

• C03B37/02763

  Fibres having axial variations, e.g. axially varying diameter, material or optical properties (rotational spin C03B37/02745) · CPC title

• C03B37/02718

  Thermal treatment of the fibre during the drawing process, e.g. cooling (coating C03C25/10) · CPC title

• C03B37/01211

  by inserting one or more rods or tubes into a tube · CPC title

• H01S3/06729

  Peculiar transverse fibre profile · CPC title

• H01S3/06716

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