Characterization of the electromagnetic Gaussian Schell-model beam using first-order interference

Changes in the statistical properties of electromagnetic double multi-Gaussian Schell-model beams on propagation in free space

A class of electromagnetic random sources with a multi-Gaussian functional form in the spectral density and in the correlations part of the cross-spectral density matrix is introduced based on the genuine cross-spectral density-matrix theory. The analytic propagation formulas of the cross-spectral density matrix of such beams propagating in free space are derived by use of Collins' diffraction integral. With the help of analytic formulas, the evolution of statistical characteristics, i.e., the spectral density, the spectral degree of polarization, and the spectral degree of coherence for such beams in free space are analyzed numerically. Employing the multi-Gaussian functional form in the cross-spectral density matrix introduces one more freedom in the modeling of Gaussian Schell-model sources.

Experimental investigation of degree of cross-polarization for an electromagnetic Gaussian-Schell model beam

We investigate the properties of the degree of cross-polarization (DOCP) for an electromagnetic Gaussian-Schell model (EMGSM) beam in the radial direction of the cross section of the beam. The coherence and polarization features of a partially coherent light beam are engineered to construct the isotropic and non-isotropic EMGSM beams, and the resulting changes in the DOCP are examined. For experimental realization, a double-slit interferometer is utilized at the output to probe the coherence properties for different polarization components across the beam diameter of an electromagnetic source. Experimental observations infer that variation in DOCP does not become apparent for isotropic coherence widths in the orthogonal polarization directions, whereas the variation can be apparent only once both the coherence widths are distinct. Furthermore, experimentally, a special case is also investigated for which the value of DOCP goes beyond unity. The DOCP finds application in areas such as second-order intensity interference, imaging, and characterization of non-homogeneously polarized beams.

Investigation of partially coherent vector vortex beams with non-isotropic states of spatial correlation

In this work, the far-field properties of non-isotropic partially coherent vector vortex beams (PCVVBs) are investigated both theoretically and experimentally. The term non-isotropic signifies that the spatial correlations between the parallel and orthogonal electric field components are distinguishable. It is found that self-orientation and shaping of intensity profile, correlation-induced polarization and depolarization are highly dependent on both the non-isotropic correlation parameters and Poincaré-Hopf index (PHI) of the beam. The simultaneous depolarization and polarization effects are due to the difference in the input correlation parameters that alter the state of polarization (SOP) and degree of polarization (DOP) distributions. The experimental results are in good agreement with the theoretical predictions. The distinguishability of correlation parameters at the source plane leads to significant changes on its intensity profile, DOP, and SOP distributions on far-field propagation, which may found potential applications in beam shaping, detecting and imaging atmospheric lidar, optical imaging and directional transportation where the self-rotation characteristic of beam plays an important role.

Statistical features of an electromagnetic Gaussian-Schell model beam propagating through a smoke aerosol environment

In this paper, we investigate both theoretically and experimentally the statistical properties of an electromagnetic Gaussian-Schell model (EMGSM) beam propagating through polluted atmosphere specifically containing smoke aerosol medium. Experimentally, a glass chamber of 1 m length is constructed to mimic the smoky atmosphere inside the laboratory, in which incense sticks are used for smoke aerosol production inside the chamber in a time-controlled manner. An input EMGSM beam having a variable degree of coherence and degree of polarization (DOP) propagates through the aerosol medium, and its coherence and polarization features after propagation are probed. The results show that the coherence features of the vectorial beam are modified significantly by the smoke aerosol medium, while, for the given propagation length of 1 m, the polarization features remain unaffected. We also investigate the coherence features of the EMGSM beam through smoke aerosols in a particular condition when the DOP of the beam is kept zero. These results are expected to provide insights into atmospheric effects on free-space optical communication in real situations when the medium contains air pollution.