Two-dimensional Laser System Employing Two Dispersive Elements

• US 20130201560A1
• Filed: 02/07/2013
• Published: 08/08/2013
• Est. Priority Date: 02/07/2012
• Status: Active Grant

• Current Assignee: Robert H. Dueck
• Original Assignee: Robert H. Dueck
• Inventors: Dueck, Robert H.
• Granted Patent: US 9,147,990 B2
• Time in Patent Office: Days
• US Class Current: 359/569
• CPC Class Codes: G02B 27/0922 the semiconductor light source comprising an array of light emitters
• CPC Class Codes: G02B 27/095 Refractive optical elements
• CPC Class Codes: G02B 27/10 Beam splitting or combining systems polarising systems G02B27/28; mixing and splitting light signals using optical waveguides G02B6/28; beam shaping, e.g. changing the cross-sectional area, by dividing or superposing multiple light beams G02B27/0905
• CPC Class Codes: G02B 27/1006 for splitting or combining different wavelengths G02B27/1086, G02B27/141 take precedence
• CPC Class Codes: H01S 3/0071 Beam steering, e.g. whereby a mirror outside the cavity is present to change the beam direction
• CPC Class Codes: H01S 5/005 Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping H01S5/026, H01S5/18388 take precedence
• 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 5/4012 Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4062 with an external cavity or using internal filters, e.g. Talbot filters
• CPC Class Codes: H01S 5/4087 emitting more than one wavelength

Abstract

An apparatus and method for two-dimensional wavelength beam combining of a plurality of laser sources. In one embodiment, an external cavity multi-wavelength laser comprises an array of laser gain elements, two optical transform lenses, two dispersive elements, an imaging system, a deflective array, and an output coupler. First and second optical transform lenses spatially overlap optical beams in first and second dimensions forming regions of overlap at the first and second dispersive elements. The deflective array comprises a plurality of mirrors wherein each mirror deflects and rearranges the optical beams from a common row. The dispersive elements introduce wavelength discrimination that when combined with the output coupler, provide the required feedback gain. The output coupler creates a single output port for the plurality of external optical cavities established in unison with the plurality of laser emitters. The output coupler transmits a multi-wavelength output beam comprising spatially overlapped coaxial optical beams.

Claims

1. A multi-wavelength laser comprising:

a plurality of laser emitters (14), wherein each laser emitter (14) produces optical radiation having a different wavelength;

a laser emitter array (10) comprising the plurality of laser emitters (14) wherein the plurality of laser emitters (14) are arranged in a two-dimensional pattern;

a multi-wavelength beam (27) comprising a plurality of multi-wavelength row beams (29), each of the multi-wavelength row beams (29) emanating from the plurality of laser emitters (14) within a laser emitter row (12);

an imaging optics (24) positioned after the laser emitter array (10) and receiving the multi-wavelength beam (27) to generate imaged beams;

a first optical transform lens (16) positioned about one focal length from the laser emitter array (10) and receiving the multi-wavelength beam (27) and spatially overlapping the multi-wavelength beam (27) in a first dimension;

a first dispersive element (18) having a wavelength dependent dispersion in the first dimension and following the first optical transform lens (16) and receiving the spatially overlapped beams and generating parallel beams in the first dimension;

a deflective array (26) following the first dispersive element (18), wherein the imaging optics (24) are configured to reimage in at least one dimension a scaled image of the optical field near the laser emitter array (10) to a location near the deflective array (26), the deflective array (26) receiving the parallel beams and generating deflected beams;

a second optical transform lens (20) positioned approximately a focal length from the first dispersive element (18) and configured to receive the multi-wavelength beam (27) and to spatially overlap the optical beams in a second dimension forming a second region of overlap at the second dispersive element (22), the second optical transform lens (20) receiving the deflected beams and generating transformed beams; and

a second dispersive element (22) following the second optical transform lens (20) and having wavelength dependent dispersion in a second dimension and configured to receive the transformed beams and transmit a multi-wavelength output beam (28) comprising the a plurality of spatially overlapped optical beams.

2. The multi-wavelength laser of claim 1, further including a first optical transform lens (16) positioned approximately a focal length from the laser emitter array (10) and configured to receive the multi-wavelength beam (27) and to spatially overlap the optical beams in a first dimension forming a first region of overlap at the first dispersive element (18).

3. The multi-wavelength laser as claimed in claim 1, wherein the first dispersive element (18) is a first-order diffraction grating.

4. The multi-wavelength laser as claimed in claim 1, wherein the first dispersive element (18) is a prism.

5. The multi-wavelength laser as claimed in claim 1, wherein the second dispersive element (22) is a first-order diffraction grating.

6. The multi-wavelength laser as claimed in claim 1, wherein the second dispersive element (22) is a prism.

7. The multi-wavelength laser as claimed in claim 1, wherein the first optical transform lens (16) comprises a plurality of lens elements having focus power in at least one dimension.

8. The multi-wavelength laser as claimed in claim 1, wherein the first optical transform lens (16) comprises a plurality of mirror elements having focus power in at least one dimension.

9. The multi-wavelength laser as claimed in claim 1, wherein the second optical transform lens (20) comprises a plurality of lens elements having focus power in at least one dimension.

10. The multi-wavelength laser as claimed in claim 1, wherein the second optical transform lens (20) comprises a plurality of mirror elements having focus power in at least one dimension.

11. The multi-wavelength laser as claimed in claim 1, wherein the imaging optics (24) comprises a plurality of lens elements having focus power in at least one dimension.

12. The multi-wavelength laser as claimed in claim 1, wherein the imaging optics (24) comprises a plurality of mirror elements having focus power in at least one dimension.

13. The multi-wavelength laser as claimed in claim 1, wherein:

the deflective array (26) comprises a plurality of deflective elements (31); and

at least one deflective element (31) element is a mirror.

14. The multi-wavelength laser as claimed in claim 1, wherein:

the deflective array (26) comprises a plurality of deflective elements (31); and

at least one deflective element (31) is an optical wedge.

15. The multi-wavelength laser as claimed in claim 1, wherein:

the laser emitter array (10) comprises a plurality of laser emitters (14) arranged in a first number of rows R; and

the deflective array (26) comprises at least R-1 deflective elements (31).

16. The multi-wavelength laser as claimed in claim 1, wherein:

the deflective array (26) comprises at least two deflective elements (31); and

at least two deflective elements (31) are arranged to each deflect at least one multi-wavelength row beam (29).

17. The multi-wavelength laser as claimed in claim 1, wherein:

the plurality of laser emitters (10) is a plurality of laser gain medium; and

further comprising a partially reflecting output coupler (38) configured to receive the multi-wavelength beam (27) at a location after both the deflective array (26) and the first dispersive element (18) and to reflect a portion of the multi-wavelength beam (27) and to transmit a remaining portion of the multi-wavelength beam (27).

18. The multi-wavelength laser as claimed in claim 1, wherein the plurality of laser emitters (14) is a plurality of fiber lasers.

19. The multi-wavelength laser as claimed in claim 1, wherein the plurality of laser emitters (14) is a plurality of semiconductor diode lasers.

20. A method of two-dimensional wavelength beam combining in a laser system, the method comprising:

generating a multi-wavelength beam (27) using an emitter array (10);

bending individual wavelength beams within row beams of the multi-wavelength beam (27) to be mutually parallel and overlapping in a first dimension using a first dispersive element (18);

deflecting the mutually parallel and overlapping in the first dimension beams to be mutually parallel and overlapping in the first dimension using a deflective array (26);

bending the mutually parallel and overlapping in the first dimension beams in a second dimension in a second dispersive element (22) to generate a multi-wavelength output beam (28).

21. The method as claimed in claim 20, further comprising imaging a scaled image of the optical field near the laser emitter array (10) using imagine optics (24) in at least one dimension to a location near the deflective array (26).

22. The method as claimed in claim 20, further including bending the individual wavelength beams of the multi-wavelength beam (27) in a first optical transform lens (16) to overlap the individual wavelength beams of the multi-wavelength beam (27) in the first dimension at the first dispersive element (18).

23. The method as claimed in claim 22, further comprising imaging a scaled image of the optical field near the laser emitter array (10) using imagine optics (24) in at least one dimension to a location near the deflective array (26).

24. The method as claimed in claim 22, further including bending the individual wavelength beams of the multi-wavelength beam (27) in a second optical transform lens (20) to overlap the individual wavelength beams of the multi-wavelength beam (27) in the second dimension at the first dispersive element (22).

25. The method as claimed in claim 24, further comprising imaging a scaled image of the optical field near the laser emitter array (10) using imagine optics (24) in at least one dimension to a location near the deflective array (26).

26. The method as claimed in claim 20, further including bending the individual wavelength beams of the multi-wavelength beam (27) in a second optical transform lens (20) to overlap the individual wavelength beams of the multi-wavelength beam (27) in the second dimension at the first dispersive element (22).

27. The method as claimed in claim 26, further comprising imaging a scaled image of the optical field near the laser emitter array (10) using imagine optics (24) in at least one dimension to a location near the deflective array (26).

28. A method of two-dimensional wavelength beam combining in a laser system, the method comprising:

generating a multi-wavelength beam (27) using an emitter array (10);

bending individual wavelength beams within row beams of the multi-wavelength beam (27) to be mutually parallel and overlapping in a first dimension using a first dispersive element (18);

bending the mutually parallel and overlapping in the first dimension beams in a second dimension in a second dispersive element (22) to generate a multi-wavelength output beam (28); and

deflecting all of the beams within each row of the multi-wavelength beam (27) in the first dimension to make all of the individual beams forming the multi-wavelength output beam (28) to be parallel and overlapping using a deflective array (26).