Abstract

Third-order frequency mixing process (ω_VUV = ω_OUV − ω_UIR) has been used to generate coherent VUV radiation between 1200 and 1220 Å. Input tunable UV radiation is obtained by summing the YAG fundamental at 1.06 μ. and the double dye laser radiation between 5400 and 5500 Å, while the fixed IR input is from the YAG. We emphasize that our experimental scheme can generate hydrogen lyman-α radiation at 1215.6 Å, and 1202.8 Å for the two-photon excitation 1s²-1s2s ¹S0 in helium using a single tunable laser. The enhancement effects on and near the two-photon resonance 4p-5p [5/2]₂ in krypton have been studied. Improved conversion efficiency has been observed by phase matching negatively dispersed krypton with positively dispersed xenon or argon in this region. With UV input powers of 200,120, and 100 kW, the generated VUV powers of 80, 320, 40 W have been obtained at 1202.8,1206, and 1215.6 Å. The dependence of the VUV powers on the pressures and the mixtures of the gases has provided useful information of the wavevector mismatch values of the media which we compare with calculations.

© 1990 Optical Society of America