Resonant peak in the output spectral profile of an ionic anti-Stokes Raman laser

Continuous-wave generation of the anti-Stokes Raman laser is demonstrated in the new L scheme Ar II 3d8 G9/2→4p8 F7/2→4s8 D5/2 with quasimetastable initial and final levels. Red pump radiation with wavelength lp5611 nm from a dye laser that excites transition 3d8 G9/2→4p8 F7/2 is converted into the blue radiation at l5461 nm (4p8 F7/2→4s8 D5/2) with efficiency of about 30%. The tunability range spans more than 20 GHz around exact resonance, which is five times broader than the Doppler contour. The output frequency v is found to depend linearly on the frequency vp of the pump field: v.vplp /l . A sharp peak of output power is observed in the spectral profile at the exact resonance instead of the well-known two-photon dip. The model is proposed that includes ionic scattering in plasma and interaction of the running pump and standing output waves. The theory offers an interpretation of the observed peak.