High beam quality of ultraviolet radiation generated through resonant enhanced frequency doubling of a diode laser

摘要

The infrared emission from an external-cavity-tapered diode laser is frequency doubled in a 5-mm #beta#-BaB_2O_4 crystal that is placed in a resonant-enhancement cavity. For a coupled diode power of 535 mW, 100 mW of continuous-wave, second-harmonic power is generated at #lambda#=392 em. The ultraviolet (UV) beam is measured to have a nearly ideal beam-quality parameter, M~2 approx= 1, in both meridians even though substantial double refraction is present in the nonlinear crystal. Printing of an array of submicron dots on a phase-change film is demonstrated with this UV beam. Also, by printing on photochemical film we demonstrate that improved film sensitivity is possible when a UV source is used.