Capillary tube to strip back-reflected light

Patent metadata

Field	Value
Publication number	US-11831121-B2
Application number	US-202117788677-A
Country	US
Kind code	B2
Filing date	Jan 28, 2021
Priority date	Jan 30, 2020
Publication date	Nov 28, 2023
Grant date	Nov 28, 2023

Abstract

Some embodiments may include a fiber laser including two or more input fibers and an output fiber to deliver a beam to a workpiece, the fiber laser comprising. The fiber laser may include a combiner having ends and a length, wherein the combiner is arranged to release, from its length, a portion of back-reflected light received from the output fiber at an output end of the ends from the combiner, the combiner including: a capillary tube to enclose part of the two or more input fibers at an input end of the ends of the combiner, the capillary tube having ends and a length located between the ends of the capillary tube; and a cladding light stripper (CLS) defined by part of the length of the capillary tube, wherein the CLS provides the release of the portion of the back-reflected light. Other embodiments may be disclosed and/or claimed.

First claim

The invention claimed is:

1. An optical fiber assembly including two or more input fibers and an output fiber to deliver a beam to a workpiece, the optical fiber assembly comprising:
a combiner having ends and a length, wherein the combiner is arranged to release, from its length, a portion of back-reflected light received from the output fiber at an output end of the ends from the combiner, the combiner including:
a capillary tube to enclose part of the two or more input fibers at an input end of the ends of the combiner, the capillary tube having ends and a length located between the ends of the capillary tube; and
means for stripping light integrated with part of the length of the capillary tube, wherein the light stripping means provides the release of the portion of the back-reflected light;

wherein a face of one of the ends of the capillary tube has an outer diameter that is smaller than a diameter of a core of the output fiber, wherein some of the back-reflected light enters the face of the end of the capillary tube from an overlapping part of the core.

2. The optical fiber assembly of claim 1 , further comprising a housing enclosing at least the part of the length of the capillary tube, wherein part of an interior of the housing is arranged to absorb light at a wavelength associated with the back-reflected light.

3. The optical fiber assembly of claim 2 , wherein the housing defines a chamber, wherein the part of the length of the capillary tube is located within the chamber, and wherein the chamber is sized to provide a gap between the interior of the chamber and an outer surface of the part of the length of the capillary tube.

4. The optical fiber assembly of claim 3 , wherein the outer surface comprises notches arranged to direct the back-reflected light to the part of the interior of the housing that is arranged to absorb light at a wavelength associated with the back-reflected light.

5. The optical fiber assembly of claim 1 , wherein an outer surface of the part of the length of the capillary tube is roughened.

6. The optical fiber assembly of claim 1 , wherein the combiner comprises a signal combiner.

7. The optical fiber assembly of claim 1 , wherein the capillary tube tapers to the output end of the combiner or otherwise includes a tapered section.

8. The optical fiber assembly of claim 7 , wherein the part of the length of the capillary tube in which the light stripping means is integrated comprises a non-tapered part of the length of the capillary tube.

9. The optical fiber assembly of claim 1 , wherein the output fiber is fused to the output end of the combiner.

10. An optical fiber assembly including two or more input fibers and an output fiber to deliver a beam to a workpiece, the optical fiber assembly including:
a combiner having ends and a length, wherein the combiner is arranged to release, from its length, a portion of back-reflected light received from the output fiber at an output end of the ends from the combiner, the combiner including:
a capillary tube to enclose part of the two or more input fibers at an input end of the ends of the combiner, the capillary tube having ends and a length located between the ends of the capillary tube, wherein an output end of the ends of the capillary tube has an inner diameter that is less than a diameter of the output fiber and the portion of the back-reflected light enters a material of the capillary tube via a face of the output end of the capillary tube; and
a cladding light stripper (CLS) defined by part of the length of the capillary tube, wherein the CLS provides the release of the portion of the back-reflected light from an outer surface of the part of the length of the capillary tube.

11. The optical fiber assembly of claim 10 , further comprising a housing enclosing at least the part of the length of the capillary tube, wherein part of an interior of the housing is arranged to absorb light at a wavelength associated with the back-reflected light.

12. The optical fiber assembly of claim 11 , wherein the housing defines a chamber, wherein the part of the length of the capillary tube is located within the chamber, and wherein the chamber is sized to provide a gap between the interior of the chamber and the outer surface of the part of the length of the capillary tube.

13. The optical fiber assembly of claim 12 , wherein the outer surface comprises notches arranged to direct the back-reflected light to the part of the interior of the housing that is arranged to absorb light at a wavelength associated with the back-reflected light.

14. The optical fiber assembly of claim 11 , wherein the housing includes a first side and a second side, wherein the first side of the housing is thermally coupled to a heat sink, wherein part of the second side of the housing defines a bottom or sides of a chamber, and wherein the at least the part of the length of the capillary tube is positioned in the chamber; and
a cover thermally coupled to the second side of the housing, wherein part of an underside of the cover defines a top of the chamber.

15. The optical fiber assembly of claim 14 , wherein the housing is formed from a first material, and the cover is formed from a second material that is different than the first material, and wherein:
the first material has a coefficient of thermal expansion that is more closely matched to a coefficient of thermal expansion of a material of the optical fiber than the second material, or
the second material has a thermal conductivity that is greater than the first material.

16. The optical fiber assembly of claim 15 , wherein the heat sink is formed from a third material, wherein the third material has a thermal conductivity that is greater than the first material.

17. The optical fiber assembly of claim 14 , wherein:
the bottom or the sides of the chamber comprise have a first reflectivity, and wherein the part of the underside of the cover comprises a second reflectivity that is less than the first reflectivity, or
the sides of the chamber are sloped to reflect the released light away from the optical fiber.

18. An optical fiber assembly including an optical fiber having a first end, a second end, and a length, wherein light is released from part of a length of the optical fiber, the optical fiber assembly comprising:
a combiner having ends and a length, wherein the combiner is arranged to release, from its length, a portion of back-reflected light received from an output fiber at an output end of the ends from the combiner;
wherein an input face of the output fiber is joined to a face of an output end of the ends of the combiner, and wherein the portion of the back-reflected light enters a material of the combiner via the face of the output end of the combiner; and
a cladding light stripper (CLS) defined by part of the length of the combiner, wherein the CLS provides the release of the portion of the back-reflected light from the part of the length of the combiner.

19. The optical fiber assembly of claim 18 , further comprising:
a heat sink;
a housing having a first side and a second side, wherein the first side of the housing is thermally coupled to the heat sink, wherein part of the second side of the housing defines a bottom or sides of a chamber, and wherein said part of the length of the optical fiber assembly is positioned in the chamber; and
a cover thermally coupled to the second side of the housing, wherein part of an underside of the cover defines a top of the chamber.

20. The optical fiber assembly

Assignees

• Nlight Inc

Inventors

• Lugo Juan Carlos
• Kokki Teemu
• Farrow Roger
• Kliner Dahv A V

Classifications

• H01S3/0064 Primary

  Anti-reflection devices, e.g. optical isolaters (absorbing layers for marking or protecting purposes in laser working B23K26/50; magneto-optical non-reciprocal devices G02F1/093, G02F1/0955) · CPC title

• H01S3/06704

  Housings; Packages · CPC title

• G02B6/255

  Splicing of light guides, e.g. by fusion or bonding · CPC title

• H01S3/067

  Fibre lasers · CPC title

• B23K26/0613

  having a common axis (B23K26/0619 takes precedence) · CPC title