Manipulating Electromagnetic Wave Propagating.and Scattering At Metaboundaries

For a long time,the free control of electromagnetic wave transmission and scattering has been an important research goal in the field of electromagnetism.Maxwell’s electromagnetic theory,which is both concise and comprehensive,provides a reliable theoretical basis for realizing this goal.According to Maxwell’s equation,the flexible construction of electromagnetic boundary conditions is an important way to control the transmission and scattering of electromagnetic waves,which is helpful to realize many novel electromagnetic phenomena.However,the boundary conditions in nature are usually too simple,so that the electromagnetic interface is limited in manipulating the propagation and scattering of electromagnetic waves.In fact,the electromagnetic interface in dielectric-dielectric structure and dielectric-metal structure can be reduced to the same form of boundary conditions.In recent years,many researchers have carried out research on the construction of new forms of electromagnetic interfaces,and have designed quite a number of different forms of electromagnetic interfaces using deep subwavelength scale electromagnetic materials,such as low-dimensional materials or metasurface.At present,the work of electromagnetic interface manipulating the propagation and scattering of electromagnetic waves is too fragmented and has not formed a system.In this paper,the possible forms of electromagnetic boundary conditions are discussed from the macroscopic point of view of electromagnetics,and they are summarized as a systematic description of the electromagnetic interface with 32 variable parameters.On this basis,the modulation of electromagnetic wave propagation and scattering by electromagnetic interface is studied deeply.The modulation of electromagnetic wave propagation and scattering by artificial special interface is further realized,and many novel electromagnetic phenomena are predicted and verified.This paper has important theoretical significance for the exploration of electromagnetic wave propagation and scattering manipulated by electromagnetic interface.The main innovative achievements of this dissertation are summarized as follows:1.Revealing a new mechanism for improving the confinement of transverse electric surface waves at the interface modified by low-dimensional materials.Using the Maxwell’s equation in isotropic medium,the general dispersion relationship of transverse magnetic and transverse electric surface waves at the interface modified by low dimensional materials is obtained analytically.The effects of surface conductivity and environmental electromagnetic properties at the transverse magnetic and transverse electric surface wave were systematically analyzed,and the mechanism of effectively enhancing the confinement of transverse electric graphene surface wave by using the negative refractive-index environment was revealed.The effects of environment temperature,electron relaxation time and graphene chemical potential on the transverse electric graphene surface waves in negative refractive-index environment were investigated in detail.Optimization of these influencing factors could further enhance the confinement of the transverse electric graphene surface waves.2.A new phenomenon of perfect polarization conversion of electromagnetic waves at the interface modified by twisted bilayer low-dimensional materials is found.A mathematical model of far field electromagnetic scattering at the interface modified by twisted bilayer low-dimensional materials is established.Based on the boundary conditions constructed by the modified interface,the most general analysis of the scattering at the modified interface is carried out.The parameter requirements of realizing the perfect polarization conversion of electromagnetic wave are found.3.Realizing the surface wave iso-frequency curves topological transformation by modifying the interface with twisted multilayer low-dimensional materials.The dispersion relationship of surface waves supported by monolayer,bilayer and multilayer low-dimensional material modified interfaces are derived analytically,and the influence of surface conductivity on the topological shape of iso-frequency curves in modified interfaces is clarified.It is found that the interlayer distance of the bilayer lowdimensional material has a great influence on the robustness of surface waves directional excitation and propagation at the modified interface.It is found that the topological transformation of iso-frequency curves is different when the surface waves supported by different types of modified interfaces(classified according to the form of surface conductivity)are coupled with each other.The interface modified by multilayer twisted low-dimensional materials provides more control degrees freedom for the topological transformation of surface wave iso-frequency curves.4.Using artificial electromagnetic interface realizes non-parasitic scattering surface wave transmission.A research scheme of surface wave transmission without adjoint scattering is proposed by using the structure of positive index dielectric-artificial electromagnetic interface-positive index dielectric.By analyzing the reflection and transmission of surface waves at discontinuous interfaces according to the classical Mie scattering theory,the parameter requirements of the surface conductivity and environmental electromagnetic properties to realize non-parasitic scattering surface wave transmission are obtained.The transmission of surface wave at discontinuous interfaces without adjoint scattering is realized,which lays a foundation for the subsequent research of surface wave as a factor for quasi-two-dimensional optics.