OPTICAL CROSS-COUPLING MITIGATION SYSTEMS FOR WAVELENGTH BEAM COMBINING LASER SYSTEMS

• US 20180373008A1
• Filed: 05/30/2018
• Published: 12/27/2018
• Est. Priority Date: 03/05/2010
• Status: Active Grant

• Current Assignee: Panasonic Corporation Of North America (Panasonic Holdings Corporation)
• Original Assignee: Bien Chann
• Inventors: CHANN, Bien
• Granted Patent: US 10,444,482 B2
• Time in Patent Office: Days
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0028 refractive and reflective surfaces, e.g. non-imaging catadioptric systems
• CPC Class Codes: G02B 19/0057 in the form of a laser diode array, e.g. laser diode bar semiconductor laser arrays with beam combining arrangement H01S5/4012
• CPC Class Codes: G02B 2005/1804 Transmission gratings
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G02B 27/1006 for splitting or combining different wavelengths G02B27/1086, G02B27/141 take precedence
• CPC Class Codes: G02B 27/4244 in wavelength selecting devices spectrometry G01J
• CPC Class Codes: G02B 6/0208 characterised by their structure, wavelength response G02B6/02114, G02B6/02171, G02B6/02195 take precedence; multiple layer cores or claddings G02B6/036, protective coverings G02B6/4429
• CPC Class Codes: G02B 6/14 Mode converters
• CPC Class Codes: G02B 6/262 Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements
• CPC Class Codes: G02B 6/29317 Light guides of the optical fibre type
• CPC Class Codes: G02B 6/32 having lens focusing means positioned between opposed fibre ends with lens being an integral part of the single fibre end G02B6/262
• CPC Class Codes: H01S 3/08063 Graded reflectivity, e.g. variable reflectivity mirror
• CPC Class Codes: H01S 5/141 using a wavelength selective device, e.g. a grating or etalon H01S5/146 takes precedence
• CPC Class Codes: H01S 5/4062 with an external cavity or using internal filters, e.g. Talbot filters
• CPC Class Codes: H01S 5/4068 with lateral coupling by axially offset or by merging waveguides, e.g. Y-couplers
• CPC Class Codes: H01S 5/4087 emitting more than one wavelength

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.

Claims

1-30. -30. (canceled)

31. A wavelength beam combining laser system comprising:

a plurality of beam emitters each emitting a beam;

a dispersive element for receiving and dispersing the beams;

a cross-coupling mitigation system for receiving and transmitting the dispersed beams while reducing cross-coupling thereof, the cross-coupling mitigation system comprising a first optical element and a second optical element, the first optical element being disposed optically upstream of the second optical element; and

a partially reflecting output coupler positioned to receive the beams transmitted by the cross-coupling mitigation system, transmit a first portion thereof as a multi-wavelength output beam, and reflect a second portion thereof back toward the cross-coupling mitigation system,

wherein (i) the first optical element is disposed within a Rayleigh range of the dispersed beams from the dispersive element, and/or (ii) the partially reflecting output coupler is disposed within a Rayleigh range of the beams transmitted by the second optical element.

32. The system of claim 31, wherein the first optical element is disposed within a Rayleigh range of the dispersed beams from the dispersive element.

33. The system of claim 32, wherein the partially reflecting output coupler is disposed within a Rayleigh range of the beams transmitted by the second optical element.

34. The system of claim 31, wherein the partially reflecting output coupler is disposed within a Rayleigh range of the beams transmitted by the second optical element.

35. The system of claim 31, wherein the cross-coupling mitigation system comprises an afocal telescope.

36. The system of claim 31, wherein a focal length of the first optical element is at least two times greater than a focal length of the second optical element.

37. The system of claim 31, wherein a focal length of the first optical element is at least seven times greater than a focal length of the second optical element.

38. The system of claim 31, wherein each of the first and second optical elements comprises a lens.

39. The system of claim 31, wherein an optical distance between the first and second optical elements is approximately equal to a sum of a focal length of the first optical element and a focal length of the second optical element.

40. The system of claim 31, further comprising focusing optics for receiving the beams emitted by the beam emitters and focusing the beams toward the dispersive element.

41. The system of claim 40, wherein an optical distance between the plurality of beam emitters and the focusing optics is approximately equal to a focal length of the focusing optics.

42. The system of claim 40, wherein an optical distance between the plurality of beam emitters and the focusing optics is greater than a focal length of the focusing optics.

43. A wavelength beam combining laser system comprising:

a plurality of beam emitters each emitting a beam;

a dispersive element for receiving and dispersing the beams;

a cross-coupling mitigation system for receiving and transmitting the dispersed beams; and

a partially reflecting output coupler positioned to receive the beams transmitted by the cross-coupling mitigation system, transmit a first portion thereof as a multi-wavelength output beam, and reflect a second portion thereof back toward the cross-coupling mitigation system,

wherein (i) the cross-coupling mitigation system is configured to receive the reflected beams and transmit the reflected beams at an angle that reduces cross-coupling into the plurality of beam emitters, and (ii) the partially reflecting output coupler is disposed within a Rayleigh range of the beams transmitted by the cross-coupling mitigation system.

44. The system of claim 43, wherein the cross-coupling mitigation system comprises an afocal telescope.

45. The system of claim 43, 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.

46. The system of claim 45, wherein the first focal length is at least two times greater than the second focal length.

47. The system of claim 45, wherein the first focal length is at least seven times greater than the second focal length.

48. The system of claim 45, wherein each of the first and second optical elements comprises a lens.

49. The system of claim 45, wherein an optical distance between the first and second optical elements is approximately equal to a sum of the first and second focal lengths.

50. A method of beam combining, the method comprising:

causing a plurality of beams to converge toward each other along a beam-combining dimension;

receiving the beams and dispersing the beams with a dispersive element;

receiving the beams from the dispersive element and transmitting the beams with a cross-coupling mitigation system, the cross-coupling mitigation system reducing cross-coupling of the beams; and

with a partially reflecting output coupler, receiving the beams transmitted by the cross-coupling mitigation system, transmitting a first portion thereof as a multi-wavelength output beam, and reflecting a second portion thereof back through the cross-coupling mitigation system toward the dispersive element.

51. The method of claim 50, wherein the partially reflecting output coupler is disposed within a Rayleigh range of the beams transmitted by the cross-coupling mitigation system.

52. The method of claim 50, wherein (i) the plurality of beams are emitted by a plurality of beam emitters, and (ii) the beams reflected back through the cross-coupling mitigation system by the partially reflecting output coupler are transmitted as stabilizing feedback to the plurality of beam emitters.