The mechanism of the CW sodium-vapor/hydrogen laser

Measurements have been carried out to gain information on the mechanism of the cw 9 m sodium-vapor/hydrogen laser 2]. Observations were carried out on the laser excited with both cw and pulsed discharges and the low-power gain of various gas mixtures was measured using tunable diode lasers. The laser was found to oscillate with mixtures of sodium vapor with H₂, D₂ and HD, but with no other gas. On substituting D₂ for H₂ a more than three-fold increase in laser gain was observed. The results showed that most of the processes used to explain lasing action in other metal-vapor lasers were not applicable to the present case. It was concluded that the primary process which leads to the production of the population inversion involves differential quenching of the laser levels by molecular hydrogen, with the lower 3D level being quenched more efficiently than the upper 4P level. Measurements carried out on the calcium/hydrogen laser 21] with D₂ supported these conclusions.