Generation of coherent radiation near 125 nm by two-photon resonant four-wave sum frequency generation in Hg vapor

Coherent radiation near 125 nm is produced by 6 1 S 0 −7 1 S 0 two-photon resonant four-wave sum frequency generation (ω 4 = 2ω 1 + ω 3 ) in Hg vapor. The two-photon resonant enhancement and two-photon resonant Kerr effects have been investigated. The optimum phase-matching conditions for both plane waves and focused beams are analyzed. Signals of four-wave parametric oscillation and four-wave difference-frequency generation have also been observed