Patent ID: 7792162

Claim:
A laser apparatus selectable between two or more frequencies of output laser light, the laser apparatus comprising: a resonator cavity comprising mirrors or reflectors, and coatings thereon, to achieve high reflectivity for wavelengths in the cavity to simultaneously resonate at least first and second laser light beams in the cavity, each beam being of a different wavelength; at least one gain medium locate in the resonator cavity for generating the laser light beams; a tunable non-linear medium located in the cavity to frequency convert at least two different frequencies, disposed in the cavity to select at least one of the first and second laser light beams to be frequency converted to a frequency altered laser light beam comprising a single converted wavelength by tuning thereof, wherein the non-linear medium converts the selected laser beam(s) by a non-linear interaction selected from the group of second, third or fourth harmonic generation, sum frequency generation, difference frequency generation and otherwise-frequency-transformed generation not comprising Raman frequency conversion; a tuner to tune the tunable non-linear medium and to select the at least one laser beam from the group of the at least first and second laser beams; and an output coupler to output two or more different frequencies of output laser light for outputting the frequency altered laser light beam from the cavity, wherein the two or more different frequencies are derived from at least one of the first and second laser light beams; wherein the tunable non-linear medium is tuned to selectively frequency convert at least one of the first and second laser light beams to the frequency altered laser light beam.