Theoretical Research On Parametric Conditions And Characteristics Of Vectorial Light Beam On Propagation And Scattering

During the last two decades, theoretical studies on electromagnetic beams on propagation and scattering through random medium had gradually shown much importance to many fields such as free space optical communications, objective detection, optical information process etc, which had already attracted attentions by scholors either internal or abroad. Among these fields, properties of vectorial beams upon propagation and scattering together with invariant conditions for degree of polarization and coherence both had become hotspots for researches. Based on the theory of vetorial beams on propagation and scattering together with unified theory of coherence and polarization, this paper deals with the theoretical models related to the propagation and scattering of general-typed Gauss, non-uniform polarized beams etc. through turbulence and uniaxial crystals etc. The conditions for beam paramters in order to remain invariant spectral degree of coherence or polarization upon propagation or scattering are derived, respectively. The main contents can be separated into following four parts:The Propagation of general-typed Gauss beams. Based on the vectorial angular spectrum representation and the method of stationary phase, vectorial structures and energy flux distributions of genral-typed Guass beams both are derived and correspondingly presented by numerical results. The conclusion is made that the far-zone energy flux distributions of these beams would be affected by various parameters in certain roles; based on the normalized Collins diffraction function, the research related to the the propagation of scalar coherent four-petals beams is further extended into the partially coherent and partially polarized case. Effects of beam parameters on the resultant field are analyzed, respectively. It is verified that the spatial correlations of vectorial beams paly major role to variations of propagation characteristics of beams upon propagation. Other than these results, based on the unifled theory of coherence and polarization of electromagnetic waves, parametric conditions for the raditions of vectorial Hermite-Gauss and cosh-Gauss beams are derived, respectively. The conclusion is made that, in order to generate these beams, coherence lengths and waist widths of source beams should obey certain inequalities.The propagation of stochastic electromagnetic beams through turbulence and optical systems. Based on the extended Huygens-Fresnel diffraction function, intensity distributions and spreading of partially coherent four-petal Gauss beams through turbulence are analyzed by numerical simulations. The theoretical method is proposed that one may control the quality of beams upon propagation turbulence by suitably modifying the coherence lengths and orders of beams; the parametric condition for invariant states of polarization of stochastic electromagnetic beams upon propagation through trubulence are derived, furthermore, this condition is verified to be valid for beams propagating through arbitrary optical systems. It is shown that this condition is independent of various impactions such as constant structures of turbulence etc. Besides, the spectral shift and spectral switch of partially coherent Gauss Schell-model beams through optical resonators are also analyzed.The propagation of non-uniform polarized beams through uniaxial crystals. Based on the theory of vectorial beams through uniaxial crystals, propagation characteristics (intensity, polarization, spreading, and kutosis parameters) of culindrically polarized vectorial beams, Lorentz beams etc. have been derived and further depicted by numerical examples, respectively. The effect of anistropic property of crystals to beams is specifically demonstrated. Besides, the condition for invariant degree of cross-polarization of stochastic electromagnetic beams through uniaxial crystals is derived. The parametric condition for beams to remain invariant intensity fluctuations in uniaxial crystals is also derived in certain equalities.The scattering of vectorial plane waves through random medium. Under the accuracy of frrst-order Born approximation, the condtion for invariant spectral degree of coherence of scalar plane waves through random medium is further extended into the case that vectorial plane waves on scattering. Differences between above two cases are specifically discussed; furthermore, effects of spatial correlations of incident plane waves on this condition are analyzed in detail. Other than above results, the correlation function between intensity fluctuations for scalar scattering case is further extended into the vectorial scattering case. It is demonstrated that both variations of polarization of incident waves together with scattering angles are two major factors which may induce differences in analytical forms for above two cases.