The observation of a stimulated electronic Raman scattering (SERS) on 3s–4s transition in sodium vapor pumped by a PTP dye laser is reported. Infrared output (Stokes) tunable from 2.38 μm to 2.65 μm has been obtained as the dye laser is tuned from 334.0 nm to 338.8 nm. Maximum photon conversion efficiency is about 30%.
We report the first observation of a cone radiation at 5890–5896 Å (ωL) in sodium vapor pumped by an excimer laser–dye laser tunable over a 334–347-nm (ωP) range. Simultaneously, with the cone radiation two tunable stimulated emissions were detected: the 3S–4S (Ω) stimulated electronic Raman scattering transition at 2.38–2.65 μm (ωS), and the 4S–3P transition at 1.138–1.142 μm (ωT). On the hollow ring of the upward cone radiation three spectral lines appear at 5890, 5896, and 5894 Å. The first two wavelengths are fixed and the third is slightly tunable during the tuning of the dye laser. The cone size varies with the sodium vapor pressure and it disappears, while the buffer argon pressure is higher than 20 Torr.
The conversion of a visible dye laser output into tunable infrared (IR) laser radiation via stimulated Raman scattering in Cs vapor was investigated. Small-signal gain, threshold intensity, and conversion efficiency measurements were obtained versus pump laser detuning. Fixed-frequency IR outputs at other wavelengths were also observed. One of these, the7P_{3/2}-5D_{5/2}transition, had a strong lasing component polarized perpendicular to the pump laser polarization. Lasing near the 8523-Å resonance line was attributed to a four-wave parametric interaction as a plausible generation mechanism.