Vacuum ultraviolet anti-Stokes Raman lasers

Anti-Stokes Raman laser schemes in atomic sulphur and selenium are studied, allowing conversion of laser lines out of the 350- 178 nm range into the 200-130 nm range. The necessary population inversion with respect to the atomic metastable
¹
S
0
levels is produced by photodissociation of the molecules COS and COSe with F
2
and ArF laser radiation, respectively. Anti-Stokes laser radiation at 167.5 and 158.7 nm for Se and at 182.0, 148.7, and 148.3 nm for S has been generated. Threshold pump energies of 0.1-20 μJ and output energies up to 5 μJ have been observed. At present, the systems are operated at low pump energies, just above threshold. It is expected that by the use of much higher pump energies and by further improvement of system parameters, output energies in the mJ range at MW peak powers will be possible for the VUV transitions.