Statistical properties of electromagnetic twisted Gaussian Schell-model array beams during propagation

An analytical model for electromagnetic twisted Gaussian Schell-model array (EM TGSMA) beams is introduced. We derive the analytical expression for the cross-spectral density matrix (CSDM) of such beam propagating in free space and investigate the spectral density, degree of polarization (DOP) and degree of coherence (DOC) in detail. Twist effects of the evolutions of DOC and DOP during propagation are also demonstrated. It is found that the twist effects of DOC and DOP can be influenced by the beam width and coherence length. In particular, senses of rotation can also be controlled by adjusting the twist strength. Furthermore, we find that twist phase always causes DOC to rotate in an opposite direction compared with that of DOP. Our results might be beneficial for free-space communications of the partially coherent beams endowed with twist. (c) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement