Research On The Propagation Of Vortex Electromagnetic Waves In Multilayer Media

Vortex electromagnetic waves appear as a new multiplexing method due to its orbital angular momentum and spiral phase wavefront,which can efficiently solve the problem of speed and channel capacity in multiplexing communication.On the other hand,electromagnetic waves often propagate across multilayer media in many fields such as seismic monitoring,geological prospecting,oil exploration,satellite communications,and optical component design.Therefore,it is very important to study the propagation characteristics of vortex electromagnetic waves in layered media in this thesis.First,the Bessel vortex beam,as a body wave,is the superposition of a series of plane waves.The angular spectrum form of the Bessel vortex beam is obtained based on the vector angular spectrum theory and Fourier transform.The validation of the method is performed and the vector Bessel vortex beam based on the angular spectrum theory in this thesis is correct.Secondly,angular spectrum expressions of the obliquely incident,reflected and transmitted Bessel vortex beams are obtained by using the reflection and transmission theory of plane waves propagation through uniaxial layered media.Based on the generalized reflection and transmission coefficient method to derive the total reflection coefficient and transmission coefficients of the uniaxial isotropic multilayer media.The reflection and transmission of the x linearly polarized Bessel vortex beam illuminating the isotropic three-layer inhomogeneous media containing SiO2,Al2O3,and Ti2O3 is numerically simulated.The results show that the total electric field intensity of the transmitted Bessel vortex beam is slightly reduced by comparing with the incident beam.The electric field is changed from a circularly symmetrical shape into an elliptical symmetrical shape and a serious shift occurrs.The electric field of the reflected Bessel vortex beam is severely distorted and shifted.Then,the reflection and transmission coefficients of the Bessel vortex beam incident on the uniaxial anisotropic single-layer media and the multi-layer media are derived based on constitutive parameters of the tensor and generalized propagation matrix method.The total reflection and transmission coefficients of the transverse electric and transverse magnetic wave are got by linearly combining the self-and cross-coupling reflection and transmission coefficients.Therefore,the reflection and transmission of x linearly polarized Bessel vortex beams through the calcite slab and three-layer media containing calcite slab,quartz,and ice are numerically simulated respectively.The results show that the transmitted Bessel vortex beam still maintain a similar profile to the original beam by comparing with the incident beam.The multi-reflection and multi-transmission of Bessel vortex beam in the three-layer media cause the distortion of the Bessel vortex beam in the three-layer media is more serious than that in the single layer media.Finally,electromagnetic characteristics of the Bessel vortex beam propagating from intermediate layer to the infinite space are given.In order to satisfy the continuous boundary conditions of tangential vectors,the transverse and longitudinal field components of electromagnetic waves of the Bessel vortex beam are derived by decomposing the Hamiltonian algorithm.Then,the expression of electromagnetic field with wave amplitude of each layer is derived by using the variable separation method and solving the active wave equation that is satisfied in the multilayer media where the Bessel vortex beam is located.The area where the Bessel vortex beam is located satisfies the active wave equation.On this basis,the propagation of the Bessel vortex beam across the sea-air interface in the shallow sea is numerically calculated.The results show that the electromagnetic field generated by the Bessel vortex beam in the air is axially symmetrical,and the amplitudes of the z and ? components of electric field is much larger than those of magnetic field.Moreover,the amplitude of the ?components of electric field is obviously prominent on the center ring,and it attenuates sharply as the distance from the center ring increases.