Spectral modifications of partially coherent light passing through a periodic sequence of lenses

Abstract

Changes in the spectrum of light passing through a periodic sequence of lenses separated by Gaussian amplitude filters are investigated theoretically on the basis of the modal expansion of the field within the framework of coherence theory in the space-frequency domain. The initial light launched into the structure is assumed to be polychromatic, spatially incoherent light with a single spectral line. By considering generally that the initially incoherent light becomes partially coherent after its propagation through the structure and by referring to the recent studies on the correlation-induced spectral changes of the Wolf effect, we satisfactorily manifest the trends in the spectral modifications that are due to the light propagation. Representative results of the analysis are illustrated by some numerical examples. As a result, the shift of the peak spectrum on the light propagation is found to depend strongly on the position of the observation. In addition, the contribution of each mode to the total spectral changes is also discussed, mainly from the viewpoint of the Wolf effect.