Picosecond optical radiation systems and methods of use

A method for shifting wavelength of a picosecond optical radiation pulse, the method comprising:

• generating a pulse of optical radiation at a first wavelength and having a duration less than 1000 picoseconds,
• pumping a wavelength-shifting resonator, operating without use of a modelocker or a Q-switch, with the pulse of optical radiation at the first wavelength, the wavelength-shifting resonator comprising a laser crystal with a high absorption coefficient at the first wavelength,
• wherein a round trip time of the wavelength-shifting resonator is shorter than pumping laser pulse duration;
• and
• extracting a pulse of radiation at a second wavelength emitted by the wavelength-shifting resonator, wherein the pulse at the second wavelength also has a duration of less than 1000 picoseconds.

A method for treating tattoos or skin pigmentation disorders using a picosecond optical radiation source, the method comprising:

• employing a pump radiation source to generate a pulse of optical radiation at a first wavelength, wherein the pulse has a duration of less than 1000 picoseconds,
• pumping a wavelength-shifting resonator, operating without use of a modelocker or a Q-switch, with the pulse of optical radiation at the first wavelength, the wavelength-shifting resonator comprising a laser crystal with high absorption coefficient at the first wavelength,
• wherein a round trip time of the wavelength-shifting resonator is shorter than the pumping laser pulse duration;
• extracting a pulse of radiation at a second wavelength emitted by the wavelength-shifting resonator, wherein the pulse at the second wavelength also has a duration of less than 1000 picoseconds;
• delivering the pulse of radiation at the second wavelength to a frequency-doubling crystal so as to generate a pulse of radiation at a third wavelength, wherein the pulse at the third wavelength also has a duration of less than 1000 picoseconds;
• and
• directing the pulse at the third wavelength to a tattoo pigment or a skin pigmentation target to disrupt the target and promote clearance thereof.