Influence of active medium on the mode structure of optical resonator near the loss degeneracy point

Abstract

Mode competition in confocal unstable resonators loaded with gain-saturable active medium is discussed. Confocal unstable resonators with magnification M = 2 are investigated, with attention focused on resonators with Neq = 3.8924. A numerical approach for searching efficiently stable solutions in cases where the traditional iterative method converges too slow is employed. Two active-medium models, the Rigrod model and CO(2) flow laser model are utilized. Ranges of resonator and medium parameters for stable one-mode lasing are determined. Similar calculations are performed for unstable axisymmetric confocal resonators.