New regime of conical emissions in multi-level optically-pumped atomic vapors

Abstract

We present experimental results of spectral and spatial properties of the laser-pumped cascade emissions from sodium vapor when the 3 S 1 2 4 P 1 2 , 3 2 transitions of sodium are excited with resonant 330 nm narrowband radiation. We observe a pronounced hollow-conical emission of the 3P3S cascade transition only. The angle and frequency of the hollow-conical radiation depend on the sodium number density. A qualitative theoretical approach that explains the observed effects is outlined.