Analytical study of the beam quality of a diode-pumped alkali laser with unstable resonator

Analytical model of Cs diode-pumped alkali laser with unstable confocal resonator is reported. Two of the parameters characterizing the quality of the output beam were studied: the axial luminous intensity in the far field and the power in the bucket (PIB). The far-field axial light intensity and PIB were compared with their values for a truncated Gaussian reference beam whose aperture was limited by the aperture of the large resonator mirror and 99% of the Gaussian beam energy passed through the aperture of this mirror. For large values of the unstable resonator magnification factor m > 5, the far-field axial light intensity is approximately 40% larger than that of the Gaussian reference beam. Analysis of the PIB curves showed that for large m > 5, the values of the integrated fractional encircled power within a sufficiently large diffraction angles for the unstable resonator exceed its values for the reference Gaussian beam. © 2024 Elsevier B.V.