Wavelength beam combining laser systems with micro-optics
In various embodiments, wavelength beam combining systems feature multiple beam emitters each emitting an individual beam, as well as multiple micro-optics arrangements each disposed optically downstream from a beam emitter to intercept the beam emitted thereby and direct the beam toward a dispersive element for combination into a multi-wavelength output beam.
1. A multi-wavelength beam combining laser system for combining a plurality of beams along a beam combining dimension into a multi-wavelength beam comprising optical radiation having a plurality of wavelengths, the laser system comprising:
a plurality of beam emitters each emitting a beam, each beam including a chief ray;
a combining optical element arranged to receive the plurality of beams, and cause the chief ray of each beam to converge along the beam combining dimension, wherein the combining optical element has a focal length;
a dispersive element, positioned along the beam combining dimension, to (i) receive the plurality of chief rays transmitted by the combining optical element, (ii) disperse the chief rays along the beam combining dimension, and (iii) transmit the dispersed chief rays; and
a partially reflective output coupler arranged to receive the dispersed chief rays transmitted by the dispersive element, to reflect a portion of the dispersed chief rays toward the dispersive element, and to transmit the multi-wavelength beam,
wherein (i) the combining optical element is disposed at a first optical distance, traversed by the beams, away from the plurality of beam emitters, (ii) the combining optical element is disposed at a second optical distance, traversed by the beams, away from the dispersive element, and (iii) the second optical distance is less than the focal length of the combining optical element.
2. The system of claim 1 , wherein the dispersed chief rays constitute a plurality of beams transmitted by the dispersive element.
3. The system of claim 1 , further comprising a beam path adjuster positioned downstream of the output coupler and configured to modify an optical path of the multi-wavelength beam.
4. The system of claim 3 , wherein the beam path adjuster is configured to modify an entrance angle of the multi-wavelength beam into an optical fiber.
5. The system of claim 3 , wherein the beam path adjuster is rotatable.
6. The system of claim 3 , further comprising a focusing optical element positioned downstream of the beam path adjuster.
7. The system of claim 1 , wherein the combining optical element is repositionable with respect to the dispersive element to alter a beam quality of the multi-wavelength beam transmitted by the output coupler.
8. The system of claim 1 , further comprising a spatial combiner system configured to provide feedback to each beam emitter from the partially reflective output coupler along a non-beam combining dimension.
9. The system of claim 1 , wherein the first optical distance is less than the focal length of the combining optical element.
10. The system of claim 9 , wherein the dispersed chief rays at least partially overlap each other spatially at the dispersive element.
11. The system of claim 9 , wherein:
each beam emitted by the plurality of beam emitters comprises one or more diverging rays,
the dispersive element (i) receives diverging rays, (ii) disperses the received diverging rays, and (iii) transmits the dispersed diverging rays, and
the dispersed diverging rays do not completely overlap spatially with the dispersed chief rays at the dispersive element.
12. The system of claim 11 , wherein the combining optical element does not cause diverging rays to converge along the beam combining dimension.
13. The system of claim 11 , further comprising, disposed downstream of the dispersive element and upstream of the output coupler, collimating optics for collimating the dispersed diverging rays transmitted by the dispersive element.
14. The system of claim 9 , further comprising a second combining optical element (i) disposed upstream of the dispersive element, and (ii) having a second focal length, wherein:
the second combining optical element is disposed at a third optical distance, traversed by the beams, away from the plurality of beam emitters, the third optical distance being substantially equal to the second focal length,
the second combining optical element is disposed at a fourth optical distance, traversed by the beams, away from the dispersive element, the fourth optical distance being less than the second focal length,
at least one beam emitted by the plurality of beam emitters comprises one or more diverging rays, and
the second combining optical element collimates, along the beam combining dimension, diverging rays received by the dispersive element.
15. The system of claim 1 , wherein the dispersed chief rays do not completely overlap each other spatially at the dispersive element.
16. The system of claim 1 , wherein a beam quality of the multi-wavelength beam is degraded as a function of the second optical distance.
17. The system of claim 1 , wherein at least two of the beam emitters are angled with respect to each other, whereby beams emitted thereby are not parallel to each other.
18. The system of claim 1 , further comprising, disposed optically downstream of the beam emitters, a plurality of micro-optics arrangements for rotating the emitted beams to thereby converge the beams toward each other.
19. The system of claim 1 , wherein at least one of the beam emitters comprises a fiber laser.
20. The system of claim 1 , wherein each of the beam emitters comprises a fiber laser.
21. The system of claim 1 , wherein the dispersive element comprises a diffraction grating.