Abstract
We introduce three-dimensional (3D) stationary, electromagnetic Gaussian Schell-model (GSM) sources in the space-frequency domain and derive the realizability conditions that the source parameters must obey. In particular, we extend to 3D GSM sources two approaches to the realizability conditions presented previously for beam-like GSM sources. The results are of interest in the analysis and synthesis of tunable non-paraxial, partially coherent, partially polarized light fields.