Continuous anti-Stokes-Raman laser oscillation in an argon-laser plasma

Generation of continuous anti-Stokes-Raman laser (ASRL) oscillation between the 3d/sup 2/P and 4s/sup 2/P levels of the argon-ion laser plasma is described. Pump radiation of 648.3 nm (610.3 nm) is up-converted into 437.5-nm radiation with an overall efficiency of more than 20% and an output power of up to 150 mW. Thus far, a detuning of +or-9 GHz around the 4p/sup 2/S intermediate resonance was achieved. The experiments reported have demonstrated that the gain on a normal laser transition may be strongly increased by population transfer and due to coherent processes. Therefore the ASRL technique in general also demonstrates a possibility to overcome the problem of insufficient mirror reflectivities in the vacuum ultraviolet (VUV) region.>