Cross-spectral purity of nonstationary vector fields in space-time and space-frequency domains

We establish the concept of cross-spectral purity for nonstationary electromagnetic fields having any degree of coherence or polarization. The conditions of cross-spectral purity in all Stokes parameters are derived for both space-time and space-frequency domains, which demonstrate that the normalized two-point coherence properties of such fields can be expressed as products of a spatial and a time (or frequency) dependent function. We further determine the condition of strict cross-spectral purity for nonstationary fields, which establishes the equivalence of normalized two-point Stokes parameters governing the spatial factors of the space-frequency and space-time domains. This study may provide interesting aspects of statistical properties of beams obtained from practically available sources such as pulsed lasers, modulated and fluctuating light sources, etc. (C) 2021 Optical Society of America

Automated summary

In this study, the concept of cross-spectral purity for nonstationary electromagnetic fields with any degree of coherence or polarization is established, and conditions for cross-spectral purity in all Stokes parameters are derived in both space-time and space-frequency domains. The research may provide interesting insights into the statistical properties of beams from various light sources.