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

Patent metadata

Field	Value
Publication number	US-9778448-B2
Application number	US-201514964700-A
Country	US
Kind code	B2
Filing date	Dec 10, 2015
Priority date	Mar 5, 2010
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

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 optical fiber for receiving the multi-wavelength beam, the optical fiber comprising (i) a core having, at an end of the optical fiber, a partially reflective outer surface for (a) receiving the multi-wavelength beam, (b) reflecting a first portion thereof back to the array of beam emitters via the dispersive element, wherein the first portion stabilizes each of the beams to its wavelength, and (c) transmitting a second portion thereof as an output beam composed of multiple wavelengths, and (ii) surrounding the core, a cladding having an outer surface (a) partially defining an end surface of the optical fiber along a diameter of the optical fiber and (b) having a reflectivity to the multi-wavelength beam of less than 1%.

2. The laser system of claim 1 , wherein a portion of the core protrudes from the cladding.

3. The laser system of claim 1 , wherein the optical fiber is positioned such that, at the partially reflective surface of the core, a diameter of the core is not less than a diameter of the multi-wavelength beam.

4. The laser system of claim 1 , further comprising an end cap attached to the optical fiber and disposed optically upstream of the partially reflective surface of the core.

5. The laser system of claim 1 , further comprising an anti-reflective coating disposed over the cladding of the optical fiber.

6. The laser system of claim 1 , further comprising a mode stripper disposed around at least a portion of the core of the optical fiber.

7. 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.

8. The laser system of claim 7 , wherein the partially reflecting surface of the core of the optical fiber is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the cross-coupling mitigation system.

9. The laser system of claim 7 , 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.

10. The laser system of claim 7 , wherein the cross-coupling mitigation system comprises an afocal telescope.

11. The laser system of claim 7 , 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.

12. The laser system of claim 11 , wherein the first focal length is at least two times greater than the second focal length.

13. The laser system of claim 11 , wherein the first focal length is at least seven times greater than the second focal length.

14. The laser system of claim 11 , wherein each of the first and second optical elements comprises a lens.

15. The laser system of claim 11 , wherein the first optical element is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the dispersive element.

16. The laser system of claim 11 , wherein the partially reflecting surface of the core of the optical fiber is disposed within a Rayleigh range of the multi-wavelength beam transmitted by the second optical element.

17. The laser system of claim 11 , wherein an optical distance between the first and second optical elements is approximately equal to a sum of the first and second focal lengths.

18. The laser system of claim 1 , wherein the partially reflective outer surface of the core has a reflectivity to the multi-wavelength beam of less than approximately 15%.

19. The laser system of claim 1 , wherein the partially reflective outer surface of the core has a reflectivity to the multi-wavelength beam ranging from approximately 2% to approximately 10%.

20. The laser system of claim 1 , wherein the partially reflective outer surface of the core has a reflectivity to the multi-wavelength beam ranging from approximately 4% to approximately 10%.

Assignees

• Chann Bien
• Teradiode Inc

Inventors

• Chann Bien

Classifications

• G02B6/14

  Mode converters · CPC title

• H01S5/4068

  with lateral coupling by axially offset or by merging waveguides, e.g. Y-couplers · CPC title

• G02B6/29317

  Light guides of the optical fibre type · CPC title

• G02B19/0014

  at least one surface having optical power · CPC title

• G02B27/1006

  for splitting or combining different wavelengths (G02B27/1086, G02B27/141 take precedence) · CPC title