Magneto-electric Coupling Mode In Three Layer Asymmetric Meta-surface

Meta-surface is a two-dimensional array of subwavelength particles,and plays a special role in the control of light.Meta-surface has attracted large attention in recent years due to the ease of fabrication and smaller insertion losses.These inclusions,so-called meta-atoms,which show the specific response to external electromagnetic field.Therefore,it is very important to study the electromagnetic properties and resonant mode of the meta-atoms.In this thesis,we use the approximation method to calculate the polarizability tensor of various meta-atoms with different shapes and materials.Also,we associate the polarizability tensor of a single particle with the properties of the meta-surfaces by the interaction constants.In addition,we analyze the magneto-electric resonant mode of the three layer meta-atoms with C3 symmetric structure,and design meta-surfaces with special reflection coefficient.The main research works of this thesis are summarized as follows:1.Based on the electric dipole approximation and the magnetic dipole approximation,the polarizability tensor of an isolated nanoparticle is calculated by the scattered far fields and the influence of symmetry on the polarizability is analyzed.The interaction constants between particles in the periodic array are calculated by different methods.Combining with the polarizability tensor and the interaction constants,we can calculate the effective polarizability tensor,the transmission coefficient and reflection coefficient of the meta-surfaces.2.We have studied the response of the particles and meta-surfaces to the electromagnetic field.In addition to the electric resonance mode,the magnetic resonance mode and magneto-electric resonance mode are introduced by changing the structure of the particles.The change of the particle structure parameters and the size of the periodic array has a great influence on the resonance frequency and intensity.With the different symmetry,the magneto-electric resonance mode of the metal-dielectric-metal three layer structure which is asymmetric in the z direction is changed,and the different reflection coefficient of the meta-surface can be obtained with the plane wave opposite propagation direction.Moreover,we study the magneto-electric mode in the heterogeneous structure,which enrich the way of controlling the light.The highlights of the thesis are as following:1.We represented the response of a particle to an external field by the polarizability tensor,and the polarizability tensor is calculated by the scattered far fields.Different from the usual integral method,we calculate the interaction constants of periodic arrays by using Green's function summation method.So,we can get the optical properties of meta-surfaces with the polarizability tensor and interaction constants.2.With the mode analysis of the metal-dielectric-metal three layer particles and the meta-surfaces structure,we get the magneto-electric resonance mode beyond the electric resonance mode and magnetic resonance mode.We use the C3 symmetry metal-dielectric-metal three layers particles to analyze the influence of magneto-electric mode on the reflection coefficient,and realize the design of meta-surfaces with special reflection characteristics.Also,we present the magneto-electric resonance mode in the heterogeneous structure.