The Propagation Of Vector Bessel Vortex Beams In Uniaxial Anisotropic Media

The vector Bessel vortex beam(VBVB)is a kind of typical vortex beam carrying orbital angular momentum,which can be treated as a new freedom degree in space mode multiplexing technology.Besides,VBVB has the characteristics of non-diffraction and selfconstruction,which promote its application prospects in optical communication,imaging,and material processing.At present,the properties of such beams have been fully studied.However,in the practical environment,the interaction mechanism between VBVBs and media,and the influence of different media on the propagation characteristics are still the key prerequisites for the application in communication,imaging and other fields.Aiming at studying the propagation characteristics of VBVBs in uniaxial anisotropic media,the reflection and transmission of obliquely incident VBVBs with different polarization mode by uniform/multilayered,lossy/lossless uniaxial anisotropic media are analyzed based on the transformation relationship between different vector wave functions,the vector wave function expansion method,and the boundary conditions of electromagnetic field.The main works are as follows:1.By using the rotation addition theorem and the transformation relationship between spherical vector wave functions(SVWFs)and cylindrical vector wave functions(CVWFs),the expression of electric field for arbitrary oblique incident vector Bessel vortex beam is derived.The expansion coefficients of three special polarization modes(linear polarization,circular polarization,and radial polarization)are given,and the correctness of this method is preliminarily verified by qualitatively comparing with the analytical results.2.Through the unknown spectrum amplitude and Fourier transform,the cylindrical vector wave function expansion of the internal field of uniaxial anisotropic media is derived.The boundary condition equation is then established with the expressions of incident,reflected,and transmitted fields,and the corresponding expansion coefficients are solved.The correctness and accuracy of the method are verified by the degradation of Bessel vortex beam,the normal incidence on isotropic media,and the quantitative comparison with analytical results.On this basis,the reflection and transmission of a VBVB by a uniaxial anisotropic dielectric slab are numerically simulated.The influence of incident angle and polarization mode on the electric field and phase distributions,as well as the orbital angular momentum state distributions of VBVB during propagation,are analyzed.Numerical results show that the method proposed in this paper has high accuracy in studying the propagation of VBVBs in uniaxial anisotropic media.The incident angle and polarization mode of the incident beam have obvious effects on the electric field profiles of reflected and transmitted fields as well as the distributions of orbital angular momentum state.3.The cascade expression of expansion coefficients of multilayered uniaxial anisotropic slab is derived.Then the reflection and transmission of multilayered uniaxial anisotropic dielectric slab are solved by the cascade expression.The energy flux density,the change of polarization,and the orbital angular momentum state distribution of VBVB during the propagation are analyzed.In addition,the effects of dissipation of media on the orbital angular momentum state distributions of reflected and transmitted beams are discussed.The results show that the inhomogeneity and dissipation of media can seriously affect the propagation of the VBVB.In particular,the dissipation of uniaxial anisotropic media can reduce the derivation of the non-dominant orbital angular momentum state of the reflected beam,which may play an important role in the multiplexing/demultiplexing technology.4.Based on the principle of generating Bessel beam by an axicon,a zero-order vector Bessel beam and a high-order VBVB are produced experimentally.Furthermore,the propagation experiments of a high-order VBVB are carried out.The intensity profiles of the transmitted field by an isotropic slab under different incident angles are obtained.The experimental results are compared with the numerical results,which are in good agreement.