Abstract
Ultraviolet radiation is generated in two lithium tetraborate (Li2B4O7 or LB4) crystals by Type I walk-off compensated sum-frequency mixing (SFM) of the commonly available Nd:YAG laser radiation and radiation from a dye laser pumped by the second harmonic of the same YAG laser. In the walk-off compensated configuration, an enhancement in the conversion efficiency by a factor of 3.8 relative to the single pass generation is realised.