High-efficiency single-frequency cw ring dye laser

A cw dye laser is described that provides tunable, high-power single-frequency radiation over the entire visible spectrum. Central to the design is the elimination of spatial hole burning and the enhancement of mode competition through the use of a ring resonator and a very-low-loss Faraday-effect device to select a single traveling-wave direction. As much as 0.9 W of single-frequency 580-nm radiation is available from rhodamine 6G using a 4-W 514.5-nm argon-ion laser pump. Intracavity second-harmonic generation has produced over 20 mW of tunable single-frequency ultraviolet radiation under the same conditions.