Enhanced production of coherent vuv radiation by four-wave mixing in Sr vapor

Abstract
Significant enhancement of the unsaturated conversion efficiencies of four-wave sum frequency mixing processes involving autoionizing states in Sr vapor is obtained by utilizing the 5s7s 1S0 two-photon channel and phase matching by frequency adjustment. Extrapolation to low power levels indicates that production of cw vuv radiation may be possible. A saturation effect arising from depletion of one of the fundamental beams by two-photon absorption is observed.