High power single mode fiber laser

Patent metadata

Field	Value
Publication number	US-10951000-B2
Application number	US-201615764147-A
Country	US
Kind code	B2
Filing date	Sep 20, 2016
Priority date	Sep 29, 2015
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

A single mode (SM) high power laser system is configured with a laser source outputting a single mode or low mode kW-power light and a passive delivery fiber spliced to an output fiber of the fiber laser source and having a double bottleneck-shaped core. The latter is configured to increase a threshold for nonlinear effects in general and in particular for stimulated Raman scattering (SRS) so that the delivery passive fiber has a fiber length at least twice the length of a delivery passive fiber with a standard uniformly dimensioned core, which may be used with the same laser source, while outputting the kW-power light with an M2 factor less than 2.

First claim

The invention claimed is:

1. A high power laser system, comprising:
a laser source outputting a single mode (SM) or low order mode kW-power light and having at least one fiber gain block which has an active fiber and an output SM passive fiber;
a passive delivery fiber spliced to the output SM passive fiber of the laser source and configured to have a double bottleneck-shaped core that is monolithic and includes:
an input end section receiving the kW power light from the laser source and an output end section, the input and output end sections each having a uniform diameter which is dimensioned to support the single mode;
a uniformly-dimensioned central section located between and having a diameter greater than that of each of the input and output end sections of the core, the central section of the core being dimensioned to support multiple modes; and
input and output tapered sections extending between respective opposite ends of the central section and the respective input and output end sections,
the passive delivery fiber increasing a threshold of nonlinear effects so that the passive delivery fiber has a fiber length at least twice the length in comparison to a length of a passive delivery fiber with a uniformly dimensioned core, while outputting the kW-power light with a beam quality factor M 2 less than 2.

2. The high power laser system of claim 1 , wherein the laser source is configured to output the single mode or low order mode light in a power range varying between 1 kW and 50 kW.

3. The high power laser system of claim 2 , wherein the laser source is configured to output 1 kW-power light coupled into the passive delivery fiber with the double bottleneck-shaped core, the passive delivery fiber with the double bottleneck-shaped core being configured with the length varying between 10 and 20 meters while emitting the 1 kW light with the M 2 factor of about 1.05.

4. The high power laser system of claim 2 , wherein the laser source is configured to output 2 kW-power light coupled into the passive delivery fiber with the double bottleneck-shaped core which is configured to have the length of 4 meters while emitting the 2 kW light with the M 2 factor of about 1.1.

5. The high power laser system of claim 2 , wherein the laser source is configured to output 5 kW-power light coupled into the passive delivery fiber with the double bottleneck-shaped core which is configured to have the length of 4 meters while emitting the 5 kW light with the M 2 factor less than 1.2.

6. The high power laser system of claim 1 , wherein the laser source is configured to output 10 kW-power light coupled into the passive delivery fiber with the double bottleneck-shaped core which is configured to have the length of 2 meters while emitting the 10 kW light with the M 2 factor of about 1.5.

7. The high power laser system of claim 1 , wherein each of the input and output end sections are configured to have either identical dimensions or dissimilar dimensions.

8. The high power laser system of claim 7 , wherein the input and output end sections are configured to have the dissimilar dimensions such that the output end section is shorter than the input end section and has a length in a range between a few millimeters and tens of centimeters.

9. The high power laser system of claim 1 , further comprising a laser head, wherein the passive delivery fiber with the double bottleneck-shaped core includes at least one of a passive fiber extending between the output SM passive fiber of the laser source and the laser head or a passive fiber extending between the laser head and a workpiece to be laser beam treated.

10. The high power laser system of claim 1 , wherein the at least one fiber gain block includes an input SM passive fiber and an active fiber, the active fiber having a downstream end coupled to an input end of the output SM passive fiber.

Assignees

• Ipg Photonics Corp

Inventors

• Ferin Anton
• Fomin Valentin
• Abramov Andrey

Classifications

• B23K26/36

  Removing material (B23K26/55, B23K26/57 take precedence) · CPC title

• G02B6/241

  Light guide terminations · CPC title

• G02B6/421

  the intermediate optical component consisting of a short length of fibre, e.g. fibre stub · CPC title

• B23K26/21

  by welding · CPC title

• G02B6/4296

  coupling with sources of high radiant energy, e.g. high power lasers, high temperature light sources · CPC title