Claims
- 1. A laser comprising:
- a resonant cavity defined by a set of reflective end elements positioned to together form a closed optical path,
- a gain medium positioned along the closed optical path,
- means for exciting the gain medium to produce a laser beam within the cavity,
- at least one focusing element, the focusing element being positioned within the resonant cavity in optical alignment with the gain medium to shape a spatial mode for each wavelength in the laser beam that is supported by the laser, and
- a prism positioned as at least one of the end elements of the cavity and providing angular dispersion of the laser beam, said at least one prism having two surfaces at an angle with respect to each other, at least one of the two prism surfaces being coated with a reflective coating,
- all of the resonant cavity elements being positioned with respect to each other such that the resonant cavity supports a coexistence of a plurality of laser modes that each have a distinct propagation axis, such that propagation axes of modes having relatively longer wavelengths traverse more of the prism than propagation axes of modes having relatively shorter wavelengths, thereby resulting in addition of a negative component to the resonant cavity group velocity dispersion.
- 2. The laser of claim 1 wherein the prism is distinct from the gain medium.
- 3. The laser of claim 2 wherein only one focusing element is positioned within the resonant cavity in optical alignment with the gain medium.
- 4. The laser of either of claims 2 or 3 wherein the prism comprises an output coupler for extracting the laser beam from within the resonant cavity.
- 5. The laser of either of claims 1 or 3 wherein the gain medium comprises a solid state medium.
- 6. The laser of claim 2 wherein the gain medium comprises a semiconductor medium.
- 7. The laser of claim 2 wherein the gain medium comprises a solid state medium.
- 8. The laser of claim 7 wherein the means for exciting the gain medium is a diode pump.
- 9. The laser of claim 7 wherein the means for exciting the gain medium comprises a laser pump.
- 10. The laser of claim 9 wherein the gain medium comprises a crystal having two surfaces at an angle with respect to each other such that the crystal is fiat-Brewster cut.
- 11. The laser of claim 9 wherein the gain medium comprises a titanium:sapphire crystal.
- 12. The laser of any of claims 1, 2, or 3 wherein the prism is characterized by an index of refraction n, where n=n(.lambda.), .lambda. being a laser mode wavelength.
- 13. The laser of claim 2 wherein the two surfaces of the prism are at the complement of the Brewster angle for the prism.
- 14. The laser of claim 13 wherein the prism comprises LAKL21 glass.
- 15. The laser of claim 13 wherein the prism comprises SF10 glass.
- 16. The laser of claim 2 wherein a combination of at least one of the resonant cavity elements is characterized by a saturable absorber mechanism that supports passive modelocking of the laser beam.
- 17. The laser of claim 16 wherein at least one of the resonant cavity elements comprises a material characterized by a nonlinear index of refraction that supports Kerr-lens modelocking of the laser beam.
- 18. The laser of claim 17 wherein all of the resonant cavity elements are positioned with respect to each other to define a laser cavity closed optical path that supports a laser beam comprising pulses of less than one picosecond in duration at a repetition rate greater than 100 MHz.
- 19. The laser of either of claims 2 or 3 wherein the gain element is positioned a distance of about one focal length from the focusing element.
- 20. The laser of claim 19 wherein the prism is positioned a distance from the focusing element that is sufficient to provide net negative intracavity dispersion.
- 21. The laser of any of claims 1, 2, or 3 wherein a combination of at least one of the resonant cavity elements modulates cavity gain of the laser to thereby modelock the laser.
- 22. The laser of claim 2 wherein the at least one focusing element comprises at least two focusing elements, each of the at least two focusing elements being positioned within the resonant cavity in optical alignment with the gain medium.
- 23. A method for compensating for group velocity dispersion of a laser beam generated in a resonant cavity defined by a set of reflective end elements positioned to together form a closed optical path, a gain medium positioned along the closed optical path, a means for exciting the gain medium to produce the laser beam within the cavity, and at least one focusing element, the focusing element being positioned within the resonant cavity in optical alignment with the gain medium to shape a spatial mode for each wavelength in the laser beam that is supported by the laser, the method comprising the step of:
- passing the laser beam generated within the resonant cavity through a prism positioned as at least one of the end elements of the cavity and providing angular dispersion of the laser beam, each of the at least one prisms having two surfaces at an angle with respect to each other, at least one of the two prism surfaces being coated with a reflective coating, all of the resonant cavity elements being positioned with respect to each other such that the resonant cavity supports a coexistence of a plurality of laser modes that each have a distinct propagation axis, such that propagation axes of modes having relatively longer wavelengths traverse more of the prism than propagation axes of modes having relatively shorter wavelengths, thereby resulting in addition of a negative component to the resonant cavity group velocity dispersion to compensate for group velocity dispersion of the laser beam.
- 24. The method of claim 23 wherein the prism is distinct from the gain medium.
- 25. The method of claim 24 wherein the gain medium comprises a solid state medium capable of supporting short laser pulsing.
- 26. The method of claim 25 wherein the gain medium comprises a titanium:sapphire crystal.
- 27. The method of claim 23 wherein the prism comprises an output coupler for extracting the laser beam from within the resonant cavity and only one focusing element is positioned within the resonant cavity in optical alignment with the gain medium.
- 28. The method of claim 23 wherein the prism is characterized by an index of refraction n, where n=n(.lambda.), .lambda. being a laser mode wavelength.
- 29. The method of claim 28 wherein the prism comprises LAKL21 glass.
- 30. The method of claim 28 wherein the prism comprises SF10 glass.
Parent Case Info
This application is a continuation of application Ser. No. 08/239,541, filed on May 9, 1994, now abandoned.
Government Interests
This work is funded by the U.S. Air Force, under Contract No. F49620-91-C0091, and by the Joint Services Electronics Programs, under Contract No. DAAL03-91-0001; the U.S. government may have certain rights to this invention.
US Referenced Citations (6)
Foreign Referenced Citations (1)
Number |
Date |
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0492994 |
Jul 1992 |
EPX |
Continuations (1)
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Number |
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239541 |
May 1994 |
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