The asymptotic analysis technique for calculating the modes of unstable strip resonators is extended to include the effects of a saturable but otherwise uniform gain. Utilizing simultaneous forward and backward (in time) propagation and the Rigrod gain formula, an iterative algorithm is employed to find the intensities inside a resonator. In contrast with Fox-Li type iterations, this scheme converges rapidly and gives all the higher modes. Mode properties at critical Fresnel numbers are examined as a function of gain saturation, which is seen to reduce mode degeneracy.
© 1981 Optical Society of America
M. J. Smith, "Mode properties of a strip confocal unstable resonator with saturable gain," Appl. Opt. 20, 1611-1620 (1981)