Four-wave parametric mixing in optically inverted barium ions

Abstract

Optically inverted barium ions in the $6{p}_{(\frac{1}{2})}$ excited state served as the nonlinear medium for doubly resonant four-wave parametric generation of coherent radiation at 167 nm. The excited barium ions were produced via selective autoionization. Stimulated-emission photons at 650 nm corresponding to the $6{p}_{(\frac{1}{2})}\ensuremath{-}5{d}_{(\frac{3}{2})}$ transition were mixed with input 451-nm laser photons turned to the $6{p}_{(\frac{1}{2})}\ensuremath{-}6{f}_{(\frac{5}{2})}$ two-photon resonance to produce the 167-nm output photons.