Study On Propagation Characteristics Of Gaussian Beam Through Anisotropic Medium

In this thesis, the transmission of a Gaussian beam through a gyrotropic cylinder and the scattering of an on-axis Gaussian beam by an arbitrarily shaped uniaxial anisotropic object are studied. The main contributions of the author’s works are as follows:1. By using the Fourier transform, the electromagnetic (EM) fields in gyrotropic and uniaxial anisotropic media are expressed as a superposition of eigenplane waves. Then, based on the representations of an arbitrary plane EM wave in a convergent series of the cylindrical vector wave functions (CVWFs) and spherical vector wave functions (SVWFs), the expansions of the EM fields in gyrotropic and uniaxial anisotropic media in terms of the CVWFs and SVWFs are obtained2. By expanding the incident Gaussian beam, transmitted beam and internal beam in terms of appropriate CVWFs and by applying the boundary conditions of the EM fields, an exact analytical solution to the transmission of a Gaussian beam through a gyrotropic cylinder is formulated. Numerical results are presented for the normalized near-surface and internal field intensity distributions, and the propagation characteristics are discussed concisely.3. Based on the extended boundary condition method (EBCM), a semi-analytical solution to the scattering of an on-axis Gaussian beam by an arbitrarily shaped uniaxial anisotropic object is constructed. The incident Gaussian beam, scattered fields as well as internal fields are expanded in terms of the SVWFs, and the unknown expansion coefficients of the scattered fields are determined by using Schelkunoff’s equivalence theorem and continuous boundary conditions. Numerical results of the normalized differential scattering cross section are presented, and the scattering characteristics are discussed concisely.