Spontaneous coherent pulsations in ring-laser oscillators: simplified models

A series of simplifications is introduced in the general model for spontaneous pulsations in ring-laser oscillators. These simplifications can lead to more-efficient numerical computations and a better understanding of specific ingredients in the model. Among the approximations investigated are neglect of spectral cross relaxation, neglect of multiple-energy level equations, neglect of electric-field derivatives, and neglect of polarization derivatives. Although some of these approximations have little effect, others eliminate the spontaneous pulsations.