Parametric wave mixing enhanced by velocity insensitive two-photon excitation in Rb vapour

摘要

We demonstrate how the orientation of the Rb cell can significantly affectthe intensity and spectral characteristics of both the frequency up- anddown-converted fields generated by nonlinear processes in Rb vapour. Theefficiency of parametric wave mixing in Rb vapour excited to the 5D5/2 level bytwo-colour resonant laser light can be significantly increased by seeding theexcitation region with coherent and directional radiation at 5.23 um that isresonant with the population inverted 5D5/2-6P3/2 transition. It has been shownthat the process of velocity insensitive two-photon excitation is central tounderstanding the observed coherent blue and mid-IR light enhancements and thatthe velocity insensitive and velocity selective two-photon excitations couldproduce two co-existing but spectrally and spatially distinguishable mid-IRfields at 5.23 um.