Direct diode pumped Ti:sapphire lasers and amplifiers

1. A system for amplification of ultrafast laser pulses, comprising:

a seed source of seed light having spectral components within the Ti:sapphire gain bandwidth of 600-1080 nm;

a gain medium comprising a Ti:sapphire crystal; and

a diode pump beam source comprising a diode laser emitting within the Ti:sapphire absorption bandwidth of ˜400-600 nm; and

a cooling device for cooling the Ti:sapphire crystal to below 200 K;

wherein the diode pump beam is directed into the Ti:sapphire crystal creating a population inversion; and

wherein the seed source is passed through the population inversion region of the Ti:sapphire crystal to effect gain.

2. The system of claim 1 wherein the pump beam wavelength is below 480 nm, and wherein the system results in amplification of >1 excited states per absorbed short-wavelength photon.

3. The system of claim 1 wherein the diode pump beam source includes multiple diodes coupled into a multimode fiber optic cable with a numerical aperture below 0.22.

4. The system of claim 3 wherein the fiber optic cable has a fiber core diameter below 230 microns.

5. The system of claim 1 wherein the diode pump beam consists of wavelengths between 435 and 480 nm.

6. The system of claim 1 wherein the diode pump beam source further comprises multiple pump diodes and a polarization combining device for polarization combining beams from the multiple pump diodes.

7. The system of claim 1 wherein the diode pump beam source further comprises multiple pump diodes and a spectral combining device for spectrally combining beams from the multiple pump diodes.

8. The system of claim 1 wherein the seed source is a mode-locked Ti:sapphire oscillator.

9. The system of claim 1 , further comprising a multipass amplifier configuration placed around the Ti:sapphire gain medium.

10. The system of claim 1 wherein the Ti:sapphire crystal is thinner than the confocal parameter of the pump beam, and further comprising optics configured to re-image the pump beam onto the crystal to absorb a significant fraction of the pump light.

11. The system of claim 1 wherein the Ti:sapphire crystal is substantially less than one absorption length thick and includes a back surface configured to reflect the pump beam and the seed light.

12. The system of claim 11 , further including a heat extracting element attached to the Ti:sapphire crystal.

13. A Ti:sapphire amplification system comprising

a seed source of light;

a gain medium comprising a Ti:sapphire crystal; and

a diode pump beam source comprising a diode laser for coupling a pump beam into the Ti:sapphire crystal; and

a cooling device for cooling the Ti:sapphire crystal to below 200 K;

wherein the pump beam is contained within a beam with a numerical aperture >0.2;

wherein the crystal is configured to have a path length between 0.5-1.5 absorption lengths, crystal doping at or below 0.25% Ti by weight; and

wherein the seed source is configured to provide a seed mode size 0.8-1.6 times the pump spot size in the Ti:sapphire crystal.

14. The system of claim 13 wherein the diode pump beam source includes multiple diodes coupled into a multimode fiber optic cable.

15. The system of claim 14 wherein the fiber optic cable has a numerical aperture below 0.22.

16. An amplification system comprising:

a seed light source;

a laser crystal gain medium comprising a Ti:sapphire crystal;

a diode pump beam source; and

a cooling device for cooling the Ti:sapphire crystal to below 200K;

wherein the pump beam is focused to multiple regions in the laser crystal gain medium; and further comprising an apparatus for passing the seed light through the multiple regions in the laser crystal gain medium.

17. The amplification system of claim 16 , wherein the seed light passing apparatus comprises a regenerative amplifier cavity.

18. The amplification system of claim 16 , wherein the seed light passing apparatus comprises a multipass amplifier cavity.