Communication modes with partially coherent fields

Abstract

We develop a theory for the description of partially coherent wave fields in linear optical systems in terms of the so-called communication modes. The communication modes are the singular functions and singular values of the appropriate propagation kernels. In particular, we show that optical fields of any state of coherence may be readily propagated through deterministic systems using the modal representation based on the system properties. The relation of the communication modes to the conventional coherent-mode representation is discussed, and expressions for the effective degree of coherence in the optical system are derived. The results are illustrated by numerical examples in optical near-field geometry.