Picosecond optical radiation systems and methods of use
Methods, systems and apparatus are disclosed for delivery of pulsed treatment radiation by employing a pump radiation source generating picosecond pulses at a first wavelength, and a frequency-shifting resonator having a lasing medium and resonant cavity configured to receive the picosecond pulses from the pump source at the first wavelength and to emit radiation at a second wavelength in response thereto, wherein the resonant cavity of the frequency-shifting resonator has a round trip time shorter than the duration of the picosecond pulses generated by the pump radiation source. Methods, systems and apparatus are also disclosed for providing beam uniformity and a sub-harmonic resonator.
1. An apparatus for delivery of pulsed treatment radiation comprising:
a pump radiation source generating pumping pulses at a first wavelength, and
a wavelength-shifting resonator having a lasing medium and resonant cavity configured to receive the pumping pulses from the pump radiation source at the first wavelength and to emit pulsed treatment radiation at a second wavelength with a pulse duration shorter than the pulse duration of the pump radiation source in response thereto,
wherein the resonant cavity of the wavelength-shifting resonator has a round trip time shorter than the duration of the pumping pulses.
2. The apparatus of claim 1 , wherein the wavelength-shifting resonator operates without use of a modelocker or a Q-switch.
3. The apparatus of claim 1 , wherein the wavelength-shifting resonator emits a subnanosecond pulse.
4. The apparatus of claim 1 , wherein the wavelength-shifting resonator has a cavity length less than 10 millimeters.
5. The apparatus of claim 1 , wherein the lasing medium of the wavelength-shifting resonator comprises a neodymium-doped crystal.
6. The apparatus of claim 1 , wherein the lasing medium of the wavelength-shifting resonator comprises a solid state crystal medium selected from the group consisting of neodymium-doped yttrium-aluminum garnet (Nd:YAG) crystals, neodymium-doped pervoskite (Nd:YAP or Nd:YAlO 3 ) crystals, neodymium-doped yttrium-lithium-fluoride (Nd:YAF) crystals, and neodymium-doped, vanadate (Nd:YVO 4 ) crystals.
7. The apparatus of claim 1 , further comprising a polarizer embedded within the resonant cavity of the wavelength-shifting resonator.
8. The apparatus of claim 1 , wherein the lasing medium of the wavelength-shifting resonator is a polarizing medium.
9. The apparatus of claim 1 , further comprising a frequency-doubling crystal.
10. The apparatus of claim 9 , wherein the frequency-doubling crystal comprises a nonlinear crystal material.
11. The apparatus of claim 9 , wherein the frequency-doubling waveguide comprises a lithium triborate (LiB 3 O 5 ) material or a KTP material.
12. The apparatus of claim 1 , wherein the pump radiation source is a mode-locked laser.
13. The apparatus of claim 12 , wherein the mode-locked laser comprises an alexandrite laser.
14. The apparatus of claim 12 , wherein the mode-locked laser generates pulsed laser energy having at least about 100 mJ/pulse.
15. The apparatus of claim 1 , further comprising a treatment beam delivery system configured to apply a treatment beam to a patient's skin.
16. The apparatus of claim 1 , wherein the wavelength-shifting resonator emits a laser energy having at least about 100 mJ/pulse.
17. A method of delivering pulsed treatment radiation comprising:
generating pumping pulses, using a pump radiation source, wherein one or more pumping pulses are at a first wavelength and a first pulse duration;
transmitting the pumping pulses to a resonant cavity of a wavelength-shifting resonator; and
emitting pulsed treatment radiation at a second wavelength from the wavelength-shifting resonator, wherein one or more pulses of the pulsed treatment radiation have a second pulse duration, the second pulse duration shorter than first pulse duration,
wherein the resonant cavity has a round trip time shorter than the duration of the pumping pulses.
18. The method of claim 17 further comprising applying a treatment beam to a patient.
19. The method of claim 17 wherein the pulsed treatment radiation comprises a subnanosecond pulse.
20. The method of claim 17 further comprising applying one or more subnanosecond pulses to a patient.
21. The method of claim 17 further comprising applying one or more subnanosecond pulses to a tattoo or a region of skin pigmentation.
22. The method of claim 17 , wherein the wavelength-shifting resonator emits a laser energy having at least about 100 mJ/pulse.