Anisotropic beam pumping of a Kerr lens modelocked laser

1. A direct laser diode pumped, Kerr lens modelocked, laser comprising:

a diode pump laser that generates an anisotropic pump beam, the pump beam having a higher-beam-quality dimension and a lower-beam-quality dimension;

an oscillator cavity including a gain medium; and

optics for directly coupling the pump beam into the gain medium;

the elements constructed and arranged such that when the laser is modelocked, spatial overlap of the pump beam higher-beam-quality dimension and the KLM laser mode is improved, over spatial overlap of the pump beam higher-beam-quality dimension and the continuous wave mode.

2. The laser of claim 1 wherein the gain medium is a Ti:sapphire crystal.

3. The laser of claim 2 wherein the pump beam wavelength is below the full width at half maximum point of the absorption curve of the Ti:sapphire crystal.

4. The laser of claim 3 wherein the diode pump laser generates blue-to-violet light and produces a pump beam of at least about M 2 =1.1 in the higher-beam-quality dimension and at least about M 2 =3 in the lower-beam-quality dimension.

5. The laser of claim 1 wherein the M 2 quality of the lower-beam-quality dimension is at least about three times the M 2 quality of the higher-beam-quality dimension.

6. The laser of claim 1 including two diode pump lasers configured side-by-side, wherein the optics couple both pump beams into the gain medium in the same direction.

7. The laser of claim 6 wherein the pump lasers are configured such that the beams approach the gain medium side-by-side and overlap within the gain medium.

8. The laser of claim 1 including two diode pump lasers spectrally combined within the gain medium.

9. The laser of claim 1 further including optics to synchronize a slow axis of the pump beam with a fast axis of the pump beam.

10. The laser of claim 1 wherein the spatial overlap of the pump beam higher-beam-quality dimension and the KLM laser mode is improved by at least about two times over continuous wave mode.

11. A Kerr lens modelocked, ultrafast laser comprising:

a pump beam generator for generating an anisotropic pump beam, the pump beam having a higher-beam-quality dimension and a lower-beam-quality dimension;

an oscillator cavity including a gain medium; and

optics for coupling the pump beam into the gain medium;

the elements constructed and arranged such that when the laser is modelocked, spatial overlap of the pump beam higher-beam-quality dimension and the KLM laser mode is improved, over continuous wave mode.

12. The laser of claim 11 further comprising a second pump beam generator for generating a second anisotropic pump beam, the second pump beam having a higher-beam-quality dimension and a lower-beam-quality dimension.

13. The laser of claim 12 wherein the coupling optics couple both pump beams into the same end of the gain medium.

14. The laser of claim 13 wherein the wherein the pump lasers are configured such that the beams approach the gain medium side-by-side and overlap within the gain medium.

15. The laser of claim 14 wherein the pump beam generators comprise diode lasers and wherein the coupling optics comprise linear optical elements.

16. The method of inducing stable Kerr lens modelocking in an ultrafast laser comprising the steps of:

(a) generating an anisotropic pump beam, the pump beam having a higher-beam-quality dimension and a lower-beam-quality dimension, wherein the M 2 quality of the lower-beam-quality dimension is at least about three times the M 2 quality of the higher-beam-quality dimension;

(b) coupling the pump beam into a gain medium of the laser;

(c) constructing and arranging the laser elements such that when the laser is modelocked, spatial overlap of the pump beam higher-beam-quality dimension and the KLM laser mode is improved, over continuous wave mode;

(d) Kerr lens modelocking the ultrafast laser; and

(e) outputting ultrafast pulses.

17. The method of claim 16 , wherein step (a) generates two anisotropic beams, and wherein step (b) couples both beams into the gain medium.

18. The method of inducing stable Kerr lens modelocking in an ultrafast laser comprising the steps of:

(a) generating a first pump beam;

(b) generating a second pump beam;

(c) focusing both pump beams into a gain medium through the same side of the gain medium, such that the pump beams substantially overlap in one beam dimension substantially throughout the gain medium;

(d) constructing and arranging the elements of the laser such that when the laser is modelocked, spatial overlap of the pump beams in the overlap dimension and the KLM laser mode is improved, over continuous wave mode;

(c) Kerr lens modelocking the ultrafast laser; and

(d) outputting ultrafast pulses.