FREQUENCY DEPENDENCE OF MODAL NOISE IN MULTIMODE OPTICAL FIBERS.

Abstract

A speckle-theory approach is used to study the frequency dependence of modal noise in optical fibers. The speckle spatial correlation function is measured and analyzed with respect to source frequency, the speckle spatial frequency distribution as a function of fiber parameters, and the speckle contrast is measured as a function of fiber length for several sources and fiber types of interest. The results of the present paper should allow extension to nonmonochromatic sources.