OBSERVATION OF CW STIMULATED RAMAN EMISSION IN THE NEON 2P-]1S MANIFOLD

We report previously unobserved cw laser emission from a commercial HeNe laser. This lasing is based on near-resonant stimulated electronic Raman scattering (SERS) involving NeI 1s5 --> 2p --> 1s4, and 1s5 --> 2p --> 1s2, electronic states when the laser cavity is pumped externally by cw dye laser radiation. Two of the emitted lines [2p2 --> 1s4 (603.0 nm) and 2p2 --> 1s2 (659.9 nm); both pumped at 588.2 nm (1s5 --> 2p2)] are explored in some detail. Output power of the Raman laser has been measured as a function of the laser-atom detuning, the Ne discharge current and the pumping laser power. These Raman lines can be several times stronger than the 633 nm HeNe laser output itself. The observations are qualitatively consistent with calculations of Raman gain showing the possibility of all 14 dipole-allowed 2p --> 1s Stokes-Raman laser lines being observable with commercial HeNe lasers, given mirror coatings of sufficient spectral width.