Analysis of the 2p-manifold population distribution in a diode-pumped metastable Ar laser

The complex excited energy levels in the diode-pumped metastable Ar laser may induce harmful effects in laser cycling. Significantly, the influence of the population distribution in 2p energy levels on the laser performance is unclear yet. In this work, the absolute populations in all the 2p states were measured online by the simultaneous applications of tunable diode laser absorption spectroscopy and optical emission spectroscopy. The results showed that most atoms were populated to the 2p₈, 2p₉, and 2p₁₀ levels while lasing, and the majority of the 2p₉ population was efficiently transferred to the 2p₁₀ level with the aid of helium, which was beneficial for the laser performance.