Stimulated scattering of light in unstable resonators

A theoretical study is made of the process of stimulated scattering of light in lasers with unstable resonators. Analytic expressions are obtained for the increase in the inhomogeneity of the refractive index of the medium and of the amplitude of converging electromagnetic waves. The results indicate that this effect may be important in CO$_2$ lasers emitting pulses of $\tau\gtrsim$ 5 $\mu$sec duration.