THE GENERATION OF TUNABLE VUV COHERENT RADIATION BY FOUR-WAVE SUM-MIXING BELOW THE FIRST RESONANCE LEVEL OF Ne

Using the output of one dye laser as the fundamental wave,we have generated tunable VUV coherent radiation from 116.6nm through 119.2nm by nonresonant four-wave sum-mixing process below the first resonance level of Ne.The conversion efficiency was found to be comparatively high because of the very small dispersion in this range.We found that the four-wave sum-mixing output was proportional to the square of the gas density we offered.If we increase the gas density of Ne,the conversion efficiency is estimated to be improved by two orders.