Laser device with Kerr effect based mode-locking and operation thereof
A laser device ( 100 ), configured for generating laser pulses, has a laser resonator ( 10 ) with a gain disk medium ( 11 ) and a Kerr medium ( 12 ). The laser resonator ( 10 ) includes a first mode shaping section ( 13 ) which is adapted for shaping a circulating electric field coupled into the gain disk medium ( 11 ), and a second mode shaping section ( 14 ), which is adapted for shaping the circulating electric field coupled into the Kerr medium ( 12 ) independently of the electric field shaping in the first mode shaping section ( 13 ). Furthermore, a method of generating laser pulses ( 1 ) using a laser resonator ( 10 ) with a gain disk medium ( 11 ) and a Kerr medium ( 12 ) is described.
1. A laser device including a laser resonator, the laser resonator comprising:
a first mode shaping including multiple resonator mirrors which have a telescopic geometry including a combination of at least one convex resonator mirror and at least one concave resonator mirror, a concave-convex geometry or a superposition thereof, and which has a thin disk laser medium providing one of the multiple resonator mirrors, said first mode shaping section is for adjusting a beam diameter of a circulating electric field in the thin disk laser medium, and
a second mode shaping section which includes a Kerr medium, the second mode shaping section is for adjusting the beam diameter of the circulating electric field in the Kerr medium, wherein the first and second mode shaping sections are for adjusting the beam diameters of the circulating electric field in the thin disk laser medium and in the Kerr medium independently of each other.
2. Laser device according to claim 1 , wherein
the first and second mode shaping sections are adjacently arranged along a light path in the laser resonator, or
the second mode shaping section is arranged inside the first mode shaping section.
3. Laser device according to claim 1 , wherein
the second mode shaping section comprises a telescope with two curved resonator mirrors including a combination of at least one convex resonator mirror and at least one concave resonator mirror, or
the second mode shaping section comprises two concave resonator mirrors.
4. Laser device according to claim 1 , wherein
the second mode shaping section comprises a Newtonian or a Galilean telescope with two curved resonator mirrors.
5. Laser device according to claim 1 , wherein
the Kerr medium is arranged in the second mode shaping section, or
the Kerr medium is arranged outside of the second mode shaping section in opposite relationship relative to the first mode shaping section.
6. Laser device according to claim 1 , including at least one of the features
the Kerr medium comprises a Kerr lens optical plate or a Kerr lens mirror,
the Kerr medium is made of CaF 2 , fused silica, sapphire or glass, and
the Kerr medium has an optical path length below 6 mm.
7. Laser device according to claim 1 , wherein the laser resonator further includes at least one of
a hard aperture,
a linear (passive) gradient mirror operating as an aperture for mode-locking in the Kerr medium, and
a self starting device adapted for providing a self starting operation of the laser device, and
a spectral filtering or shaping unit arranged for shifting of a maximum gain wavelength and flattening gain spectrum of the electric field circulating in the laser resonator.
8. Laser device according to claim 1 , wherein
the Kerr medium is arranged for producing additional spectral components in the electric field circulating in the laser resonator.
9. Laser device according to claim 1 , further including at least one of
an intracavity medium acting as a nonlinear element for producing additional spectral components in the electric field circulating in the laser resonator, and
an intracavity plate acting as an output coupler for new spectral components created in the laser resonator.
10. Laser device according to claim 1 , further comprising at least one of
an evacuated box accommodating the laser resonator at reduced pressure or in vacuum,
an external fibre broadening and compression stage, and
an acousto-optical modulator being adapted for external carrier envelope phase stabilization.
11. Laser device according to claim 1 , wherein
the laser resonator is coupled with a passive enhancement cavity or with an extra cavity nonlinear crystal for white light generation.
12. A method of generating laser pulses using a laser resonator with a thin disk laser medium and a Kerr medium, said method comprising the steps of
adjusting a beam diameter of a circulating electric field in the thin disk laser medium in a first mode shaping section including multiple resonator mirrors, wherein the thin disk laser medium is providing one of the multiple resonator mirrors, and
adjusting the beam diameter of the circulating electric field coupled into the Kerr medium in a second mode shaping section, wherein,
the beam diameter of the circulating electric field in the first mode shaping section is adjusted by using a telescopic geometry including a combination of at least one convex resonator mirror and at least one concave resonator mirror, resonator mirrors having a concave-convex geometry, or a superposition of the telescopic geometry, or a superposition of the telescopic geometry and the concave-convex geometry, and
the beam diameters of said circulating electric field in the thin disk laser medium and in the Kerr medium are adjusted independently of each other.
13. Method according to claim 12 , wherein the shaping of the circulating electric field in the second mode shaping section is obtained by using
a telescope with two curved resonator mirrors including a combination of at least one convex resonator mirror and at least one concave resonator mirror, or
two concave resonator mirrors.
14. Method according to claim 12 , wherein the shaping of the circulating electric field in the second mode shaping section is obtained by using
a Newtonian or a Galilean telescope with two curved resonator mirrors.
15. Method according to claim 12 , wherein
the Kerr medium is arranged in the second mode shaping section, or
the Kerr medium is arranged outside of the second mode shaping section in opposite relationship relative to the first mode shaping section.
16. Method according to claim 12 , wherein the laser resonator further includes at least one of
a hard aperture,
a linear (passive) gradient mirror operating as an aperture for mode-locking in the Kerr medium, and
a self starting device adapted for providing a self starting operation of the laser device.
17. Method according to claim 12 , further comprising
spectral filtering of the circulating electric field for shifting of a maximum gain wavelength and flattening gain spectrum.
18. Method according to claim 12 , further comprising at least one of
producing new spectral components in the electric field circulating in the laser resonator using the Kerr medium or an intracavity medium,
out-coupling of new spectral components from the laser resonator using the Kerr medium or an intracavity plate, and
coupling the laser resonator with a passive enhancement cavity or with an extra cavity nonlinear crystal for white light generation.
19. Method according to claim 12 , further comprising
out-coupling of new spectral components from the laser resonator using the Kerr medium or an intracavity plate.
20. Method according to claim 12 , further including
adjusting the temperature at least of a part of the laser resonator.
21. Method according to claim 12 , further comprising at least one of
arranging the laser resonator in an evacuated box at reduced pressure or in vacuum,
coupling the laser resonator with an external fibre broadening and compression stage, and
an external carrier envelope phase stabilization using an acousto-optical modulator.
22. Method according to claim 12 , further comprising at least one of
arranging the laser resonator in an evacuated box at reduced pressure or in vacuum,
subjecting the laser pulses created in the laser resonator to an external fibre broadening and compressing, and
subjecting the laser pulses created in the laser resonator to an external carrier envelope phase stabilization using an acousto-optical modulator.
23. Method according to claim 12 , further comprising
coupling the laser resonator with a passive enhancement cavity or with an extra cavity nonlinear crystal for white light generation.