Wolf effect in homogeneous and inhomogeneous media

We derive expressions for the spectrum of the field produced by planar, secondary Gaussian Schell-model sources after propagation in free-space, homogeneous dispersive media, and graded-index fibers. Our results show, for the first time to our knowledge, the development of correlation-induced spectral changes (the Wolf effect) as a function of the propagation distance from the source plane. An important result of our study is the prediction of the enhancement of the Wolf effect for propagation in media of index of refraction larger than unity. In the case of graded-index fibers having a parabolic index profile, the source spectrum is shown to reproduce periodically at distances at which such fibers image the source.