Wavelength combined laser system

1. A beam combiner, comprising:

an array of source elements,

each source element, of the array of source elements, being configured to output a beam of light locked at a center wavelength different from center wavelengths of other source elements of the array of source elements;

a dispersive element configured to combine the beams of light into a combined beam;

a beam separator configured to separate the combined beam into an output beam and a locking beam,

the locking beam comprising a smaller portion of the combined beam than the output beam,

the smaller portion including a portion of the beam of light of each source element;

a spatial filter configured to prevent crosstalk within the locking beam, and to redirect the locking beam back to the array of source elements; and

the dispersive element configured to disperse the locking beam into constituent wavelength beams,

each constituent wavelength beam being directed to a respective one of the array of source elements for locking that source element at its center wavelength, and

each constituent wavelength beam corresponding in wavelength to the center wavelength of the respective source element.

2. The beam combiner of claim 1 , wherein the spatial filter comprises a reflective or transmissive filter configured to reflect or transmit, respectively, the locking beam, while transmitting or reflecting, respectively, stray light.

3. The beam combiner of claim 2 , wherein the spatial filter comprises:

a substrate with an aperture for transmitting the locking beam, while reflecting or absorbing the stray light; and

a mirror for reflecting the locking beam back through the aperture, the beam separator, the dispersive element, and to the array of source elements.

4. The beam combiner of claim 3 , wherein the spatial filter further comprises:

a first lens having a first focal plane substantially coincident with the beam separator, and a second focal plane substantially coincident with the aperture; and

a second lens having a third focal plane substantially coincident with the aperture, and a fourth focal plane substantially coincident with the mirror.

5. The beam combiner of claim 2 , wherein the spatial filter comprises:

a substrate with an aperture for reflecting the locking beam, while transmitting the stray light; and

a mirror for reflecting the locking beam back through the aperture, the beam separator, the dispersive element, and to the array of source elements.

6. The beam combiner of claim 5 , wherein the spatial filter further comprises:

a first lens having a first focal plane substantially coincident with the beam separator, and a second focal plane substantially coincident with the aperture; and

wherein the mirror comprises a concave minor having a third focal plane substantially coincident with the aperture.

7. The beam combiner of claim 2 , wherein the spatial filter comprises:

a substrate with an aperture for reflecting the locking beam to the beam separator, while transmitting the stray light.

8. The beam combiner of claim 7 , where the spatial filter further comprises:

a first lens having a first focal plane substantially coincident with the beam separator, and a second focal plane substantially coincident with the aperture.

9. The beam combiner of claim 1 , wherein the spatial filter comprises an etalon.

10. The beam combiner of claim 1 , wherein the array of source elements has a variable pitch.

11. A beam combiner, comprising:

a beam separator configured to separate a combined beam into an output beam and a locking beam,

the combined beam being a beam of light that is a combination of beams of light provided by source elements of a source array,

each source element, of the source array, being configured to output a beam of light locked at a center wavelength different from center wavelengths of other source elements of the source array, and

the locking beam including a portion of the combined beam that is smaller than the output beam,

the smaller portion including a portion of the beam of light of each source element;

a locking arm configured to prevent crosstalk within the locking beam, and to redirect the locking beam back to the source array; and

a dispersive element configured to disperse the locking beam into a group of wavelength beams,

each wavelength beam being directed to a respective one of the source elements, of the source array, for locking that source element at its center wavelength, and

each wavelength beam corresponding in wavelength to the center wavelength of the respective source element.

12. The beam combiner of claim 11 , wherein the locking arm comprises:

a spatial filter that includes a substrate with an aperture for transmitting the locking beam, while reflecting or absorbing stray light; and

a mirror for reflecting the locking beam back through the aperture, the beam separator, the dispersive element, and to the source array.

13. The beam combiner of claim 12 , wherein the spatial filter further comprises:

a first lens having a first focal plane approximately coincident with the beam separator, and a second focal plane approximately coincident with the aperture; and

a second lens having a third focal plane approximately coincident with the aperture, and a fourth focal plane approximately coincident with the minor.

14. The beam combiner of claim 11 , wherein the locking arm comprises:

a spatial filter including a substrate with an aperture for reflecting the locking beam, while transmitting stray light; and

a mirror for reflecting the locking beam back through the aperture, the beam separator, the dispersive element, and to the source array.

15. The beam combiner of claim 14 , wherein the spatial filter further comprises:

a first lens having a first focal plane approximately coincident with the beam separator, and a second focal plane approximately coincident with the aperture; and

wherein the mirror comprises a concave minor having a third focal plane.

16. The beam combiner of claim 11 , wherein the locking arm comprises a substrate with an aperture for reflecting the locking beam to the beam separator, while transmitting the stray light.

17. The beam combiner of claim 16 , where the locking arm further comprises a first lens having a first focal plane approximately coincident with the beam separator, and a second focal plane approximately coincident with the aperture.

18. A method, comprising:

separating, by a beam combiner, a combined beam into an output beam and a locking beam,

the combined beam being a beam of light that is a combination of beams of light provided by source elements included in a source array,

each source element, of the source array, being configured to output a beam of light locked at a center wavelength different from center wavelengths of other source elements of the source array, and

the locking beam including a portion of the combined beam that is smaller than the output beam,

the smaller portion including a portion of the beam of light of each source element;

preventing, by the beam combiner, crosstalk within the locking beam;

redirecting, by the beam combiner, the locking beam back to the source array; and

dispersing, by the beam combiner, the locking beam into a set of wavelength beams,

each wavelength beam being directed to a respective one of the source elements of the source array for locking that source element at its center wavelength, and

each wavelength beam corresponding in wavelength to the center wavelength of the respective source element.

19. The method of claim 18 , further comprising:

transmitting the locking beam while reflecting or absorbing stray light; and

reflecting the locking beam for dispersion into the set of wavelength beams.

20. The method of claim 18 , further comprising:

reflecting the locking beam while transmitting stray light; and

reflecting the locking beam for dispersion into the set of wavelength beams.