Measuring And Modeling The Beam Quality In Cesium Dpals

We report on recent experimental and theoretical studies of cesium laser, where we focused on the beam propagation factor M-2 in flowing-gas Cs DPALs with stable optical resonators and of its dependence on the resonator geometry. The measured results were modelled by multi-transverse-mode model [Auslender et al, Opt. Express 25, 19767 (2017)]. Conditions for substantial improvement of the output laser beam quality, reducing M-2 to close to unity, are found. In particular we show how changing the length of the resonator, and/or the radius of curvature of the high reflection mirror, leaving all other parameters of the laser unchanged, makes it possible to control the beam quality.