New parametric emissions in diatomic sodium molecules

By excitation of sodium vapor with an ultra-violet laser, tunable coherent emissions around 688 and 770 nm generated from diatomic sodium molecules have been observed for the first time. We demonstrate that the emission around 688 nm is due to an axially phase-matched four-wave-mixing process involving cascade emissions of 2.54 µm and 910 nm radiation from sodium dimers.