Natural fluctuations in a multimode standing-wave laser

It is shown theoretically that the relative fluctuations in the numbers of photons in individual modes of a multimode standing-wave laser with a homogeneously broadened gain profile is extremely sensitive to the degree of filling of the resonator with the active medium. If this medium fills the whole resonator, the spatial effects result in strong suppression of fluctuations in the individual modes. In the opposite case of a thin medium the statistical properties of a multimode standing-wave laser are close to those of a traveling-wave laser. The conclusions reached are used in an analysis of the quantitative discrepancy between the results of published experimental studies of the statistics of multimode lasing.