Random Electromagnetic Beam Propagation Characteristics

In recent years, the propagation characteristics of stochastic electromagnetic beams have been a subject of great interest among scientific investigations. Since the unified theory of coherence and polarization for stochastic electromagnetic beams formulated by Wolf in 2003, extensive publications have been focused on the change in the spectrum, the degree of coherence and the degree of polarization of stochastic electromagnetic beams on propagation. In this dissertation, some beams (such as Gaussian Schell-Model beams, GSM beams for short) are taken as examples to investigate the change in the spectrum, the intensity and the degree of polarization during their propagation. The following studies are included:1. Based on the propagation law of completely coherent light, the expression for spectrum in the interference field of Young's double-slit interference experiment is derived. The influence of the width of source spectrum and the width of slits on the spectral change is analyzed. It is found that the spectral shift as well as the spectral width will change with the change in the width of source spectrum and the width of slits.2. According to the propagation law of cross-spectral density and the unified theory of coherence and polarization, we study the change in the spectrum and the degree of polarization in the interference field of Young's double-slit experiment formed by a partially coherent light (GSM beam). It is shown that the spectrum and the degree of polarization in the interference field depend on the slit width and the correlation length in the source plane. Furthermore, the spectral change depends on the width of source spectrum, and the degree of polarization depends on the degree of polarization in the source plane.3. The interference fringes of Young's double-slit experiment formed by a completely coherent vortex beam are studied. It is found that the fringes shift in transversal direction along the perpendicular direction. The direction and the magnitude of the shift of the interference fringes depends on the sign and the magnitude of the topological charge, respectively.4. Starting from the propagation theory of partially coherent light, we derive the formula for the intensity distribution, the degree of coherence and the degree of polarization of aberrant stochastic electromagnetic beams. A GSM beam is taken as an example to investigate the propagation characteristics of beams with astigmatism propagating through turbulent atmosphere. The results show that the spread of beams with astigmatism is fast. The change in the astigmatic coefficient, the turbulence and the correlation of the beam will lead to the change in the degree of polarization during their propagation. In the long-propagation distance limit, the degree of polarization of the beam tends to the value in the source plane.5. Based on the unified theory of coherence and polarization, we investigate the propagation properties of random electromagnetic vortex beams. According to the numerical simulations, the inner intensity of the beams increase with the decrement of correlation length, and a large topological charge will lead to a larger dark hole. Moreover, the degree of polarization depends on the correlation length and the topological charge.