Abstract

Barium-vapor lasers (BVLs) are efficient (~0.5%), high-average-power (10–15 W), high-pulse-rate (~10-kHz) sources operating at a variety of wavelengths (1.13, 1.50, and 2.55 μm) in the mid-IR region. The 2.55-μm laser line in particular has potential applications including testing of fluoride glass optical fibers and covert surveillance. Moderate output power (~1.5 W) has recently been obtained at this wavelength for a BVL with an active volume of ~370 cm³ operated at high (200-mbar) helium-buffer-gas pressures.¹ However, the populating mechanism of the Ba ³P₂ upper laser level during the excitation phase is not yet fully understood, and this has limited the scaling capability of this transition. Measurements on a laser-pumped barium vapor² suggest that population is transferred by spin-changing collisions with rare-buffer-gas atoms from the resonantly pumped Ba ¹P₁ level. Laser-induced-perturbation studies by Pask and Piper³ have shown that population transfer to the Ba ³P₂ state also occurs by superelastic electron deexcitation from the Ba ¹P₁ state. Direct excitation of the Ba ³P₂ upper laser level directly from the Ba ¹S₀ ground state was not observed.

© 1995 Optical Society of America