We analytically demonstrate that both single-mode and multimode instabilities may occur in a Gaussian-cavity-mode laser model with Gaussian pump profile. As a necessary condition, the ratio of the beam waist to the pump waist must exceed a given limiting value, which depends on the population decay rate. For an infinitely concentrated pump the plane-wave model instability thresholds are recovered, and there exists an optimum value of the waists ratio for which the second laser threshold is minimum.
© 1998 Optical Society of America
J. F. Urchueguía, G. J. de Valcárcel, and Eugenio Roldán, "Laser instabilities in a Gaussian cavity mode with Gaussian pump profile," J. Opt. Soc. Am. B 15, 1512-1520 (1998)