V-shaped resonators for addition of broad-area laser diode arrays

• US 8,340,151 B2
• Filed: 12/13/2010
• Issued: 12/25/2012
• Est. Priority Date: 12/13/2010
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Liu, Bo, Liu, Yun, Braiman, Yehuda Y.
• Primary Examiner(s): Stultz, Jessica
• Assistant Examiner(s): Nguyen, Phillip
• Application Number:
  US12/966,423
• Publication Number:
  US 20120147471A1
• Time in Patent Office: 743 Days
• Field of Search: 372 92- 94, 372 97-103
• US Class Current: 372/98
• CPC Class Codes: G02B 27/14 operating by reflection only

Abstract

A system and method for addition of broad-area semiconductor laser diode arrays are described. The system can include an array of laser diodes, a V-shaped external cavity, and grating systems to provide feedback for phase-locking of the laser diode array. A V-shaped mirror used to couple the laser diode emissions along two optical paths can be a V-shaped prism mirror, a V-shaped stepped mirror or include multiple V-shaped micro-mirrors. The V-shaped external cavity can be a ring cavity. The system can include an external injection laser to further improve coherence and phase-locking.

Claims

1. A system for coherent addition of broad-area laser diode emissions, comprising:

an array of broad-area laser diodes, wherein each broad-area laser diode emits radiation and adjacent broad-area laser diodes are separated by a distance (d_pitch); and

a V-shaped cavity, wherein a laser beam emitted from said system is coherent at a wavelength (λ

) and wherein said V-shaped cavity comprises;

a V-shaped reflector arranged to split radiation emitted from each of said broad-area laser diodes into a first beam traveling along a first optical path and a second beam traveling along a second optical path, wherein said V-shaped reflector is selected from the group consisting of a V-shaped prism reflector, a V-shaped stepped reflector and an array of micro-prism reflectors,

a fast-axis correction lens disposed between said array of broad-area laser diodes and said V-shaped reflector,

a cylindrical lens, having a focal distance (f), and a grating arranged sequentially along said first optical path, wherein said grating is arranged to direct first-order diffraction at said wavelength (λ

) toward said array of broad-area laser diodes, and

a second cylindrical lens, having a second focal distance (f₂), and a second grating arranged sequentially along said second optical path, wherein said second grating is arranged to direct first-order diffraction at said wavelength (λ

) toward said array of broad-area laser diodes, wherein a distance along said second optical path between said second cylindrical lens and said second grating is equal to said second focal distance (f₂).

2. The system according to claim 1, wherein a distance along said first optical path between said cylindrical lens and said grating is substantially equal to a sum of said focal distance (f) and a half-Talbot distance (Z_t/2), wherein Z_t=2d_pitch²/λ

.

3. The system according to claim 1, wherein said broad-area laser diodes operate in multiple-transverse modes.

4. The system according to claim 1, further comprising a stepped, phase compensation plate arranged along said first optical path positioned between said V-shaped reflector and said cylindrical lens.

5. The system according to claim 1, further comprising:

an optical coupler arranged along said first optical path or said second optical path, wherein said optical coupler reflects a first portion of said first beam, said second beam or both, and transmits out of said system a laser beam comprising a second portion of said first beam, said second beam or both.

6. The system according to claim 1, wherein said V-shaped reflector comprises an array of micro-prism reflectors.

7. The system according to claim 6, wherein at least one of said micro-prism reflectors is independently adjustable.

8. The system according to claim 1, further comprising an external injection laser arranged to emit a locking laser beam along a second optical path into said array of broad-area laser diodes.

9. The system according to claim 1, wherein said array of broad-area laser diodes is one of a one-dimensional linear array or a two-dimensional stacked array.

16. The system according to claim 1, wherein said V-shaped reflector comprises a stepped reflector.

10. A system for coherent addition of broad-area laser diode emissions, comprising:

an array of broad-area laser diodes, wherein each broad-area laser diode emits radiation and adjacent broad-area laser diodes are separated by a distance (d_pitch); and

a V-shaped cavity, wherein a laser beam emitted from said system is coherent at a wavelength (λ

) and wherein said V-shaped cavity comprises;

a V-shaped reflector arranged to split radiation emitted from each of said broad-area laser diodes into a first beam traveling along a first optical path and a second beam traveling along a second optical path, wherein said V-shaped reflector is selected from the group consisting of a V-shaped prism reflector, a V-shaped stepped reflector and an array of micro-prism reflectors,

a fast-axis correction lens disposed between said array of broad-area laser diodes and said V-shaped reflector, and

a cylindrical lens, having a focal distance (f), and a grating arranged sequentially along said first optical path, wherein said grating is arranged to direct first-order diffraction at said wavelength (λ

) toward said array of broad-area laser diodes,

wherein said V-shaped cavity is a ring cavity and said first and second optical paths overlap in whole or in part.

11. A system for combining laser diode emissions, comprising:

an array of broad-area laser diodes, wherein each broad-area laser diode emits radiation and adjacent broad-area laser diodes are separated by a distance (d_pitch); and

a V-shaped cavity, wherein a laser beam emitted from said system is coherent at a wavelength (λ

), said V-shaped cavity comprising;

a V-shaped reflector arranged to split radiation emitted from each of said broad-area laser diodes into a first beam traveling along a first optical path and a second beam traveling along a second optical path, wherein said V-shaped cavity is a ring cavity and said first and second optical paths overlap in whole or in part, and

a fast-axis correction lens disposed between said array of broad-area laser diodes and said V-shaped reflector.

12. The system according to claim 11, further comprising:

a cylindrical lens, having a focal distance (f), and

a grating arranged sequentially along said first optical path, wherein said grating is arranged to direct first-order diffraction at said wavelength (λ

) toward said array of broad-area laser diodes, wherein a distance along said first optical path between said cylindrical lens and said grating is a sum of said focal distance (f) and a half-Talbot distance (Z_t/2), wherein Z_t=2d_pitch²λ

.

13. The system according to claim 11, further comprising:

an optical coupler arranged along said first optical path or said second optical path, wherein said optical coupler reflects a first portion of said first beam, said second beam or both, and transmits out of said system a laser beam comprising a second portion of said first beam, said second beam or both.

14. A system for coherent addition of laser diode emissions, comprising:

an array of broad-area laser diodes, wherein each laser diode emits radiation and adjacent broad-area laser diodes are separated by a distance (d_pitch); and

a V-shaped cavity, wherein a laser beam emitted from said system is coherent at a wavelength (λ

) and wherein said V-shaped cavity comprises;

a V-shaped reflector arranged to split radiation emitted from each of said broad-area laser diodes into a first beam traveling along a first optical path and a second beam traveling along a second optical path, wherein said V-shaped reflector is selected from the group consisting of a V-shaped prism reflector, a V-shaped stepped reflector and an array of micro-prism reflectors,

a fast-axis correction lens disposed between said array of broad-area laser diodes and said V-shaped reflector,

an external injection laser arranged to emit a locking laser beam along a second optical path into said array of broad-area laser diodes,

at least one optical isolator positioned along said second optical path between said external injection laser and said V-shaped reflector, wherein said at least one optical isolator prevents electromagnetic radiation emitted by said array of broad-area laser diodes from propagating to said external injection laser,

a cylindrical lens, having a focal distance (f), and

a grating arranged sequentially along said first optical path, wherein said grating is arranged to direct first-order diffraction at said wavelength (λ

) toward said array of broad-area laser diodes,

wherein said V-shaped cavity is a ring cavity and said first and second optical paths overlap in whole or in part.

15. The system according to claim 14, wherein a distance along said first optical path between said cylindrical lens and said grating is substantially equal to a sum of said focal distance (f) and a half-Talbot distance (Z_t/2), wherein Z_t=2d_pitch²/λ

.