Observation of Raman-shifted oscillation near the sodium D lines

Abstract
We have observed oscillation in the wings of the Doppler-broadened sodium D lines when they are pumped by a cw dye laser and enclosed in an optical cavity. The oscillation is blue (red) detuned from the pump laser by the ground-state hyperfine splitting of sodium when the pump-laser frequency is in the blue (red) wing. The gain mechanism is explained on the basis of optical pumping and stimulated Raman scattering.