We propose the use of a laser model in which the single-mode approximation is introduced for the electric field but not for the atomic variables. We show that our improved single-mode model is in good agreement with the exact steady-state solution for a reasonable range of experimentally relevant parameters well beyond the limits of validity of the mean-field approximation.

• Received 3 October 1985

DOI:https://doi.org/10.1103/PhysRevA.33.1109