Method for manufacturing bent optical fiber

Patent metadata

Field	Value
Publication number	US-10836672-B2
Application number	US-201815962198-A
Country	US
Kind code	B2
Filing date	Apr 25, 2018
Priority date	Aug 30, 2016
Publication date	Nov 17, 2020
Grant date	Nov 17, 2020

Abstract

Provided is a method for manufacturing bent optical fibers with which bent optical fibers having a quality difference effectively reduced can be manufactured without a reduction of the manufacturing yield. In the present embodiment, an elastic bending process and a heating process are alternately repeated. In the elastic bending process, a movement restricting member rotatable around a revolving shaft is rotated while an optical fiber having its leading end portion held by the movement restricting member is fed toward the revolving shaft to form bent portions at a part of the optical fiber. In the heating process, the optical fiber is irradiated with a laser beam to relieve stress at the bent portions. Thus, multiple bent portions at which the stress is relieved are formed in the optical fiber along the longitudinal direction of the optical fiber.

First claim

The invention claimed is:

1. A method for manufacturing a bent optical fiber including a core and a cladding, composed of silica glass, and having a bent-shaped portion, the method comprising:
a preliminary process of preparing a bend imparting mechanism that includes a revolving shaft and a movement restricting member, the movement restricting member comprising a pair of protrusions, the pair of protrusions define a gap having a width within a range of twice an outer diameter of the cladding of the optical fiber or greater to four times the outer diameter or smaller, and the movement restricting member being rotatable around the revolving shaft while holding an optical fiber to restrict a movement of the optical fiber in a direction perpendicular to a longitudinal direction of the optical fiber;
a mounting process of inserting a first end portion of the optical fiber into the movement restricting member from a side of the revolving shaft to mount the first end portion of the optical fiber on the bend imparting mechanism, and fixing a second end portion of the optical fiber to a fiber feeding mechanism; and
a bent-optical-fiber manufacturing process of forming, in the optical fiber, a plurality of bent portions apart from each other in the longitudinal direction so that the optical fiber has the bent-shaped portion,
wherein the bent-optical-fiber manufacturing process includes
an elastic bending process of the fiber feeding mechanism feeding the optical fiber toward the bend imparting mechanism to increase an inclination angle by a predetermined angle, and to form the bent portions at a part of the optical fiber having a position so adjusted as to cross the revolving shaft, the inclination angle being formed by a feed direction of the optical fiber and a perpendicular line drawn from the movement restricting member to the revolving shaft, and
a heating process of softening the bent portions by heating the bent portions through scanning of the optical fiber with a laser beam being moved in an axial direction of the revolving shaft across the optical fiber, and thus relieving stress at the bent portions, and

wherein the heating process is intermittently repeated while the inclination angle is increased stepwise every time the elastic bending process is performed, to form, in the optical fiber, the plurality of bent portions apart from each other in the longitudinal direction.

2. The method for manufacturing a bent optical fiber according to claim 1 , wherein the optical fiber is irradiated with the laser beam during a period in which an operation of tilting a position of the movement restricting member and an operation of feeding the optical fiber from the fiber feeding mechanism are both stopped.

3. The method for manufacturing a bent optical fiber according to claim 1 , wherein the laser beam is applied to the optical fiber in the axial direction to scan the optical fiber across the optical fiber between a first position, at which a laser-beam-irradiated area deviates from the optical fiber, and a second position, which is located on one side of the optical fiber across from the first position and at which the irradiated area deviates from the optical fiber.

4. The method for manufacturing a bent optical fiber according to claim 1 , wherein the laser-beam scanning in the axial direction is controlled so that an average temperature of the laser-beam-irradiated area at which the bent portions of the optical fiber are located is kept at a temperature higher than or equal to a glass softening point for a period of time shorter than or equal to 500 ms.

5. The method for manufacturing a bent optical fiber according to claim 1 ,
wherein the optical fiber includes a plurality of optical fiber components arranged side by side in the axial direction, and
wherein, in the mounting process, a first end portion of each of the plurality of optical fiber components is held by the movement restricting member, and a second end portion of each of the plurality of optical fiber components are fixed to the fiber feeding mechanism.

6. The method for manufacturing a bent optical fiber according to claim 1 , wherein the laser beam includes an infrared laser beam having a wavelength of higher than or equal to 1.5 μm.

7. The method for manufacturing a bent optical fiber according to claim 1 , wherein the increased angle by which the inclination angle of the movement restricting member is increased in the elastic bending process every time the heating process is performed is smaller than or equal to 5°.

Assignees

• Sumitomo Electric Industries

Inventors

• Nanjo Takuya

Classifications

• G02B6/2552

  reshaping or reforming of light guides for coupling using thermal heating, e.g. tapering, forming of a lens on light guide ends · CPC title

• C03B37/15 Primary

  with heat application, e.g. for making optical fibres (fusion-splicing of light guides G02B6/255; treatment of light guides to shape optical elements {G02B6/2835, G02B6/2856}) · CPC title

• B29D11/00663

  Production of light guides · CPC title

• C03B37/01

  Manufacture of glass fibres or filaments · CPC title