Tunable efficient CW ultraviolet generation in periodically poled lithium niobate

Tunable continuous wave single frequency lasers suit to applications in high resolution spectroscopy and metrology. In the given infrared second harmonic generation, efficiency is optimized by using a nonlinear material capable of non critical phase matching. Deviations from the predicted phase matched wavelengths have been measured and used to provide corrections to Sellmeir coefficients at short wavelengths. Photorefractive effects observed at all the UV wavelengths can be eliminated by heating the PPLN crystal above a critical temperature. Reduction in SHG efficiency at shorter wavelengths is attributed to UV absorption