Q-switched cavity dumped sub-nanosecond laser
Apparatuses and methods are disclosed for applying laser energy having desired pulse characteristics, including a sufficiently short duration and/or a sufficiently high energy for the photomechanical treatment of skin pigmentations and pigmented lesions, both naturally-occurring (e.g., birthmarks), as well as artificial (e.g., tattoos). The laser energy may be generated with an apparatus having a resonator with a sub-nanosecond round trip time.
1. A laser oscillator for generating laser energy having a pulse duration of less than 1 nanosecond comprising:
(a) a first mirror and a second mirror within a housing, with the first mirror and the second mirror providing a sub-nanosecond round trip time for laser radiation along an axis between the first mirror and the second mirror;
(b) an electro-optic device, a polarizer and a lasing medium positioned between the first mirror and the second mirror along the axis; and
(c) a pump source operatively coupled to the lasing medium,
(d) wherein the laser oscillator is capable of proceeding through at least three consecutive states comprising hold-off, buildup and cavity dumping.
2. The laser oscillator of claim 1 , wherein the cavity dumping state has a range of acceptable transient times that are greater than the ideal step function transient time.
3. The laser oscillator of claim 1 , wherein the cavity dumping state has a range of acceptable transient times that are greater than the ideal step function transient time, wherein a range of acceptable transient times includes from 0.5 round trip times to 5 round trip times which generates output pulse durations that range from 1 round trip time to 2.5 round trip times, the round trip time being sub-nanosecond.
4. The laser oscillator of claim 1 , wherein the first mirror and the second mirror are fixed within the housing to define a static resonator chamber having a sub-nanosecond round trip time.
5. The laser oscillator of claim 1 , wherein the lasing medium comprises Alexandrite, Ti:S, Nd:YAG, Nd:YAP, Nd:YAlO 3 , Nd:YLF, yttrium-aluminum garnet doped with a rare earth or a transition metal ion dopant, yttrium-aluminum perovskite doped with a rare earth or a transition metal ion dopant, yttrium aluminum oxide doped with a rare earth or a transition metal ion dopant, a vanadate crystal, YVO 4 , fluoride glasses, ZBLN, silica glasses, minerals, ruby, crystals or glass media hosts.
6. The laser oscillator of claim 1 , wherein the electro-optical device is a Pockels cell.
7. The laser oscillator of claim 1 , wherein the sub-nanosecond round trip time is between 500 and 900 ps.
8. The laser oscillator of claim 1 , wherein the sub-nanosecond round trip time is between 700 and 800 ps.
9. The laser oscillator of claim 1 , wherein the pump source operatively coupled to the lasing medium provides pumping radiation along a longitudinal side of the lasing medium.
10. The laser oscillator of claim 1 , wherein the pump source operatively coupled to the lasing medium provides pumping radiation along a longitudinal side of the lasing medium via an optical element.
11. The laser oscillator of claim 1 , wherein the pump source operatively coupled to the lasing medium provides pumping radiation along a longitudinal side of the lasing medium via a prism.
12. The laser oscillator of claim 1 , wherein the pump source operatively coupled to the lasing medium includes two pump sources providing pumping radiation along opposite longitudinal sides of the lasing medium via an optical element.
13. The laser oscillator of claim 1 , wherein the pump source operatively coupled to the lasing medium provides pumping radiation along an end of the lasing medium via an optical element.
14. The laser oscillator of claim 1 wherein the pump source operatively coupled to the lasing medium provides pumping radiation along an end of the lasing medium via a prism.
15. The laser oscillator of claim 1 wherein the pump source includes at least one flash lamp having an axis transverse to the optical axis of the lasing medium.
16. The laser oscillator of claim 1 wherein the pump source includes a pair of flash lamps, each flash lamp having an axis transverse to the optical axis of the lasing medium.
17. The laser oscillator of claim 1 wherein the pump source includes a plurality of flash lamps, each flash lamp having an axis transverse to the optical axis of the lasing medium.
18. The laser oscillator of claim 1 , wherein the pump source includes a manifold and a pair of flash lamps, each flash lamp extends through a flash lamp channel in the manifold, the lasing medium extends through a lasing channel in the manifold, and the lasing medium and lasing channel extend transversely with respect to the flash lamps and flash lamp channel.
19. The laser oscillator of claim 1 , wherein the pump source includes a ceramic diffuse reflector and a pair of flash lamps, the flash lamps extends through a flash lamp channel in the ceramic diffuse reflector, the lasing medium extends through a lasing channel in the ceramic diffuse reflector, and the lasing medium and lasing channel extend transversely with respect to the flash lamps and flash lamp channel.
20. The laser oscillator of claim 1 , wherein the pump source includes a pair of flash lamps, each flash lamp extends a flash lamp flow tube, the lasing medium extends through a lasing flow tube, and the lasing medium and lasing flow tube extend transversely with respect to the flash lamps and flash lamp flow tubes.
21. The laser oscillator of claim 20 , wherein the lasing flow tube has an hourglass shape and includes peripheral channels at opposed ends thereof.