Interaction Between Multilayer Dielectric Sphere And Incident Beam In Arbitrary Direction

The interaction of the multilayer dielectric sphere with tangible beams has always been a hot topic in the theoretical research and practical application,which has a guiding role and broad application prospects in biomedicine,optical manipulation,microwave antenna,and so on.In this thesis,the radar cross section(RCS)of multi-layer chiral metamaterial spheres illuminated by a plane wave and a Gaussian beam at arbitrary incident direction is discussed.The radiation force of an axially incident Gauss beam on a multilayer dielectric sphere is also analyzed.The main research results are summarized as follows:1.Based on the scattering theory of the multi-layer sphere,the scattering and extinction characteristics of the double-layer sphere are studied.The effects of various parameters on RCS of the metal sphere coated with chiral metamaterial are discussed.The analysis shows that chiral metamaterial can obviously reduce the backscattering of the coated sphere.Then,extinction characteristics of the gain spheres coated by the nanoscale metal are analyzed.It is found that there are two resonance peaks in the extinction coefficients of the coated gain sphere.The larger peak of the coated gain sphere is obviously larger than those of the pure metal sphere and gain sphere.The position and value of the resonance peak can be adjusted by changing medium parameters of the metal and coating.2.Based on the COMSOL Multiphysics simulation software,the interaction between multi-layer chiral sphere and incident beam in any direction is discussed.The scattering characteristics of a double-layer chiral sphere with spherical center coordinates at the origin and near-axis origin illuminated by incident the plane wave in arbitrary direction are analyzed in detail.Then the influence of RCS on double-layer spheres whose spherical center coordinates are not at the origin are further discussed with the incident Gauss beam along different axes.The results show that the RCS with oblique incidence can be obtained by rotating the RCS with horizontal incidence at a certain angle,if the system is symmetrical.3.The expressions of radiation force are derived and the radiation force of the multi-layer sphere is calculated.Firstly,the influence of various parameters on the radiation force of a multi-layer chiral sphere is analyzed.In addition,the radiation force of the chiral sphere coated with nanoscale metal under the incidence of Gaussian beam is simulated.The influence of chiral parameters and refractive index on the radiation force of the chiral coated sphere is discussed.The findings show that the chiral coated sphere can obtain the larger pulling force when the chiral parameter reaches a certain value.By changing the value of the chiral parameter,the pulling force can be directed in the opposite direction.The analysis of the refractive index shows the pulling force of the coated chiral sphere can be changed by adjusting the relative refractive index of the inner sphere.The larger the refractive index of the inner sphere is,the smaller the pulling force is.