Optical cross-coupling mitigation systems for wavelength beam combining laser systems

Patent metadata

Field	Value
Publication number	US-10871639-B2
Application number	US-201916559834-A
Country	US
Kind code	B2
Filing date	Sep 4, 2019
Priority date	Mar 5, 2010
Publication date	Dec 22, 2020
Grant date	Dec 22, 2020

Abstract

In various embodiments, wavelength beam combining laser systems incorporate optical cross-coupling mitigation systems and/or engineered partially reflective output couplers in order to reduce or substantially eliminate unwanted back-reflection of stray light.

First claim

What is claimed is:

1. A laser system comprising:
an array of beam emitters each emitting a beam having a different wavelength;
focusing optics for focusing the beams toward a dispersive element;
a dispersive element for receiving and dispersing the focused beams, thereby forming a multi-wavelength beam; and
an output coupler comprising (i) a beam-receiving portion for receiving the multi-wavelength beam, reflecting a first portion thereof back to the array of beam emitters via the dispersive element, and transmitting a second portion thereof as an output beam composed of multiple wavelengths, and (ii) a non-reflective portion.

2. The laser system of claim 1 , wherein the beam-receiving portion of the output coupler is at least as large as a diameter of the multi-wavelength beam.

3. The laser system of claim 1 , wherein the beam-receiving portion of the output coupler protrudes above the non-reflective portion.

4. The laser system of claim 1 , wherein the non-reflective portion at least partially surrounds the beam-receiving portion.

5. The laser system of claim 1 , wherein a reflectivity to the multi-wavelength beam of the non-reflective portion is less than 1%.

6. The laser system of claim 1 , wherein a reflectivity to the multi-wavelength beam of the beam-receiving portion is less than approximately 15%.

7. The laser system of claim 1 , wherein a reflectivity to the multi-wavelength beam of the beam-receiving portion ranges from approximately 2% to approximately 10%.

8. The laser system of claim 1 , further comprising a non-reflective coating disposed over the non-reflective portion of the output coupler.

9. The laser system of claim 1 , further comprising an end cap over the beam-receiving portion of the output coupler.

10. The laser system of claim 1 , further comprising an optical fiber positioned to receive the output beam.

11. The laser system of claim 1 , further comprising a workpiece positioned to receive the output beam.

12. The laser system of claim 1 , further comprising an optical element for focusing the multi-wavelength beam toward the output coupler.

13. The laser system of claim 12 , wherein the optical element comprises at least one of a cylindrical lens or a spherical lens.

14. The laser system of claim 1 , further comprising a cross-coupling mitigation system for receiving and transmitting the multi-wavelength beam while reducing cross-coupling thereof.

15. The laser system of claim 14 , wherein the beam-receiving portion of the output coupler is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the cross-coupling mitigation system.

16. The laser system of claim 14 , wherein at least a portion of the cross-coupling mitigation system is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the dispersive element.

17. The laser system of claim 14 , wherein the cross-coupling mitigation system comprises an afocal telescope.

18. The laser system of claim 14 , wherein the cross-coupling mitigation system comprises a first optical element having a first focal length and a second optical element having a second focal length, the first optical element being disposed optically upstream of the second optical element.

19. The laser system of claim 18 , wherein the first focal length is at least two times greater than the second focal length.

20. The laser system of claim 18 , wherein the first focal length is at least seven times greater than the second focal length.

21. The laser system of claim 18 , wherein each of the first and second optical elements comprises a lens.

22. The laser system of claim 18 , wherein the first optical element is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the dispersive element.

23. The laser system of claim 18 , wherein the beam-receiving portion of the output coupler is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the second optical element.

24. The laser system of claim 18 , wherein an optical distance between the first and second optical elements is approximately equal to a sum of the first and second focal lengths.

Assignees

• Chann Bien
• Teradiode Inc

Inventors

• Chann Bien

Classifications

• H01S3/08063

  Graded reflectivity, e.g. variable reflectivity mirror · CPC title

• G02B6/29317

  Light guides of the optical fibre type · CPC title

• G02B6/262

  Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements · CPC title

• G02B2005/1804

  Transmission gratings · CPC title

• H01S5/4087

  emitting more than one wavelength · CPC title