title: Modeling of energy-transfer upconversion and thermal effects in end-pumped quasi-three-level lasers.
abstract: An analytical model of cw quasi-three-level lasers that includes the influence of energy-transfer upconversion (ETU) has been developed. The results of the general output modeling were applied to a laser with Gaussian beams, and rigorous numerical calculations have been made to study the influence of ETU on threshold, output power, spatial distribution of population-inversion density, and fractional thermal loading. The model was applied to a laser operating at 946 nm in Nd:YAG, where the dependence of laser-beam size on laser performance was investigated in particular. A simple model for the degradation of laser-beam quality from a transversally varying saturated gain is proposed that is in good agreement with measurements of the laser in a plane-plane cavity.
authors.affiliation: Laser Physics and Quantum Optics, Department of Physics, Royal Institute of Technology, 106 91 Stockholm, Sweden. sb@laserphysics.kth.se
authors.forename: Stefan
authors.initials: S
authors.lastname: Bjurshagen
authors.forename: Ralf
authors.initials: R
authors.lastname: Koch