CW far-UV laser system with two active resonators

A laser system, comprising:

• a travelling-wave laser-resonator arranged for generating laser-radiation having a first wavelength in a wavelength range between about 900 and 1080 nanometers and arranged such that said first-wavelength radiation circulates in only one direction therein;
• an optically-nonlinear element positioned in said first laser-resonator such that said first-wavelength radiation circulates therethrough;
• and
• a second laser resonator generating laser radiation having a second wavelength between about 200 and 280 nanometers and arranged to inject said second-wavelength radiation into said optically-nonlinear crystal such that said first-wavelength radiation and second-wavelength radiation travel in the same direction therein and mix therein, thereby generating radiation having the sum-frequency of said first and second-wavelength radiations and a wavelength between about 175 and 215 nm, said sum-frequency radiation being delivered from said optically-nonlinear crystal as output-radiation.

A method of generating radiation in a wavelength range between about 175 and 215 nm, comprising the steps of:

• (a) providing a travelling-wave laser-resonator arranged for generating laser-radiation having a first wavelength in a wavelength range between about 900 and 1080 nanometers and arranged such that said first-wavelength radiation circulates in only one direction therein;
• (b) positioning an optically-nonlinear element in said active laser-resonator such that said first-wavelength radiation circulates therethrough;
• (c) injecting radiation having a second-wavelength between about 200 and 280 nanometers into said optically-nonlinear crystal such that said first-wavelength radiation and second-wavelength radiation travel in the same direction therein and mix therein, thereby generating radiation having the sum-frequency of said first and second-wavelength radiations and a wavelength between about 175 and 215 nm;
• and
• (d) delivering said sum-frequency radiation from said optically-nonlinear element as output-radiation.