Steering Of Electromagnetic Wave Propagation By Metamaterials With Dielectric Topology Structure

Metamaterial is a sub-wavelength artificial periodic structure,which is composed of resonant units.Through specific topology design,it can show unique electromagnetic properties and optical phenomena.Hyperbolic metamaterials（HMs）is an artificial composite anisotropic material with hyperbolic dispersion relationship.In terahertz and near-infrared frequency regions,HMs has great application prospects in sub-wavelength imaging,improving photon density and wide-band absorption due to its unique near-field manipulation characteristics of electromagnetic waves.With the development of nano processing technology,the two materials also provide more possibilities to control the transmission of electromagnetic waves.This paper designs several ingenious topologies to realize nonreciprocal electromagnetic wave transmission,reciprocal energy steering and coexistence,multi-mechanism optical sensing,nonlinear optical switch,controllable magnetic detection and magnetic coding.The main contents of this paper are as follows:1.The dielectric constant and group index of graphene-based HMs are studied.Firstly,the tunable single frequency absorption is realized in the transmission region in the cell structure by using the absorption characteristics of graphene and Brewster’s window.Secondly,the cell structures with different absorption peaks are spliced into a whole,which can realize the ultra-wideband absorption and the transmission window in the absorption region,and can work in different frequency bands after optimizing the parameters.In addition,the optical properties of saturated and unsaturated graphene are also investigated,and a switchable saturated-unsaturated defect mode structure based on HMs with graphene is designed,which can work in mid-infrared and near-infrared bands.The results show that a better saturated defect mode can be observed at a smaller incident angle and a larger period,while the unsaturated defect mode can be controlled by the chemical potential of graphene.By using nonlinear Kerr material,a new threshold optical system with angle memory and bistable absorption of graphene is designed for the switch structure.The two proposed graphene-based HMs structures can be used for ultra-wideband absorption,logic switch based on transmission in absorption region and nonlinear optical switch.2.The dielectric constants in three orthogonal directions of black phosphorus（BP）and silver composite HMs were studied,and the quasi-periodic structure based on HMs with BP was designed.The results show that the absorption peaks of transverse electric（TE）wave and transverse magnetic（TM）wave can be observed at different incident angles and frequency positions during the forward transmission.The overall peak value of TM wave is larger than that of TE wave,which is more suitable for angle sensor.Its sensitivity is 1.49 THz·degree^-1in the linear variation range.For the backward transmission,the whole structure presents a omnidirectional band gap（OBG）in the range of incident angle of 0°-70°and frequency of 630 THz-740 THz.Therefore,the nonreciprocal transmission of electromagnetic waves in two directions is obtained.In addition,the absorption characteristics of HMs stacked by BP and tantalum pentoxide are also discussed.Combined with the surface plasmon polariton（SPP）absorption of graphene,a direction-dependent dual-mechanism sensor composed of strip graphene and composite BP photonic structure is designed.The results show that when the refractive index measurement ranges is 1.2-1.6 and 1.6-1.9,the sensitivities of forward incidence are 3.135 THz/RIU（refractive index unit）and 1.135 THz/RIU,respectively.When the refractive index detection zones are 1.2-1.5 and 1.6-2.0,the sensitivities of backward incidence are 9.500 THz/RIU and 14.650 THz/RIU,respectively.The forward incidence has better linearity and the backward incidence possesses better angular stability.The proposed two structures can be used to realize nonreciprocal absorber,angle and refractive index sensor.3.The electromagnetic properties of magnetized plasma materials are studied,and a quasi-periodic structure（QPS）composed of magnetized plasma and ordinary dielectric is designed.The structure breaks spatial symmetry to achieve OBG,and polarization splitting（PS）is realized through the different effects of magnetized plasma on two polarized waves.The results also show that a better OBG can be observed under large plasma frequency and small applied magnetic field intensity.The smaller the plasma frequency or the greater the applied magnetic field intensity,the better the performance of PS.In addition,the dielectric constant and group index of HMs with plasma are also investigated,and an improved Thue-Morse sequence structure is proposed.By using the unique dielectric constant of HMs,the tunable single frequency reflection in absorption（SFRA）with stable angle is realized.It is found that the higher the filling rate of the plasma,the lower the SFRA frequency position,and the higher the collision frequency,the higher the SFRA frequency position.These two structures provide ideas for the design of OBG devices,PS devices and angle stable anti-dispersion waveguide structures.4.The electromagnetic properties of ferrite materials in constant magnetic field are studied,and the composite topology ferrite-based element（FBE）is designed.By stacking three FBEs with three kinds of magnetic fields,the steering of FBEs on electromagnetic wave energy in gradient magnetic domain is systematically discussed.The results show that the ultra-wideband absorption and the transmission window in the absorption band can be realized in the incident angle range of 0°-60°for the forward direction.By expanding the applied magnetic field into a pairwise symmetrical distribution,the reciprocal energy coexistence of absorption and transmission can also be realized.In addition,a logic switch with magnetic detection and magnetic coding is proposed by using the transmission window in the absorption band,which can realize the detection of specific magnetic intensity and the coding of continuous random magnetic information.These results can be used for wide-angle reciprocal energy steering,multifunctional magnetic detection and coding.5.The spin Hall effect（SHE）in superconductor materials is studied,and a periodic superconducting structure with multi-window SHE is designed.The transmission defects of p-wave and s-wave at different angles are realized by using the multi-peak and angle sensitive characteristics of evanescent wave in periodic superconducting structure.On this basis,the number of transmission peaks is controlled and the multi-window SHE is obtained.Both horizontal and vertical components have large displacement values,and the window number is inversely proportional to the displacement value.In addition,a micro-refractive index sensor is proposed by investigating the influence of the refractive index of the medium on the two kinds of displacement,and the optimal sensitivity can reach 253.9°·RIU^-1.These results provide theoretical guidance for designing multi-window SHE and high precision refractive index sensor.