Research On Electromagnetic Scattering And Optiacal Force Of Chiral Medium Sphere Based On Mie Theory

With the continuous development of the theory and the application of electromagnetic waves,electromagnetic scattering and light force for various types of complex targets have been studied more and more.Among the computational methods for studying electromagnetic scattering and optical force,Lorenz-Mie scattering method,transmission matrix method,finite-difference time-domain method,finite element method,and moment of method are commonly used.If the target object is a sphere,the Lorenz-Mie scattering method is the fastest and most accurate one.In this thesis,the method of Lorenz-Mie theory is mainly used to study the electromagnetic scattering and optical force of the chiral medium sphere.Firstly,the scattering coefficients of single-layer chiral sphere are obtained by solving and approximating spherical vector wave function.The bistatic Radar Cross Section(RCSs)of chiral sphere can be got by using the scattering coefficients.In the study of the electromagnetic properties of the chiral sphere,we find that the electromagnetic properties are changed with the different incident beams.Therefore,this thesis analyzes and summarizes the incident beams and gives the electric field distributions of the basic Gaussian beam,the Hermite Gaussian beam and the Laguerre Gaussian beam.Then,the electromagnetic scattering characteristics of chiral media spheres with different chiral parameters,permittivity and spherical thicknesses are discussed.In addition,when the chiral media spheres have negative refractive indices,the corresponding electromagnetic scattering characteristics are also different.The electromagnetic scattering characteristics of single-layer spheres are comparatively comprehensive.By using the recursive relationship between the single-layer and multi-layer,we can acquire the scattering coefficients for multi-layer spheres,and then analyze the electromagnetic properties of multilayered chiral media spheres.Finally,after the calculations of scattering coefficients of monolayer and multilayer chiral media spheres,the expression of the radial force of the chiral media sphere can be derived according to the law of conservation of momentum of electromagnetic fields.Through the expression of the radiation force of the dielectric sphere,we analyzed the electromagnetic radiation force of the chiral media sphere from several aspects.When studying the radiation force,the beams factor expressions of the beam are obtained by the electric field expression of the beams,then the axial radiation forces of the Davis Gaussian beam and the on-axis Laguerre Gaussian beam are calculated.The analyzation and research on electromagnetic scattering and radiation force of the different medium sphere can make the Mie theory widely used in biomedicine,chemical metallurgy,atmospheric environmental protection,aerospace exploration,and other aspects.