Effects of spatial non-uniformity on laser dynamics

Semiclassical equations of lasing dynamics are re-derived for a lasing medium in a cavity with a spatially non-uniform dielectric constant. It is shown that the non-uniformity causes a radiative coupling between modes of the empty cavity. This coupling results in a renormalization of self- and cross-saturation coefficients, which acquire a non-trivial dependence on the pumping intensity. Possible manifestations of these effects in random lasers are discussed.