Design And Research Of Phase Modulation Structure Of Terahertz Metamaterials

Terahertz waves have broad application prospects,and phase modulators are an important class of functional devices to realize terahertz system applications.Based on the research foundation of metamaterial structure and the application requirements of dynamic modulation,this paper studies the structure of transmissive,reflective and switchable metamaterial devices that realize the phase modulation function of terahertz waves.Using the combination of dynamically controllable materials such as vanadium dioxide and graphene with traditional design,a series of terahertz metamaterial functional devices are designed according to the needs of different application scenarios.The working principle and functional characteristics of the designed device are deeply analyzed by three-dimensional electromagnetic simulation and calculation of multipole scattering energy.(1)A dynamically tunable transmissive terahertz phase modulator was designed based on the combination of tunable material vanadium dioxide and artificial microarray structure.The design follows the classic metamaterial design method.By controlling the conductivity of vanadium dioxide,the phase can achieve 140° dynamic phase regulation in the bandwidth range of 0.5 THz without changing the structural geometric parameters.almost unchanged.(2)Based on the tunable material graphene,a reflective phase modulation structure is designed.The designed reflective phase modulation structure unit cell adopts the traditional three-layer metamaterial structure design.By rationally parameterizing the graphene in the structure,the designed structure can realize the dynamic regulation of the phase without changing the geometric parameters.In two different control modes,the structure can achieve phase changes of more than 300°.The graphene in the structure adopts a coupling design,which effectively increases the magnitude of the phase shift and significantly reduces the complexity of the unit cell structure.(3)Based on the research on the tunable materials graphene,vanadium dioxide,and transmission and reflection phase modulation structures in the previous two parts,a phase modulation structure with switchable transmission mode and reflection mode is designed.The structure adopts a multi-layer metamaterial stacking design,graphene is located in the middle part of the structure,as the key to phase modulation,and vanadium dioxide is placed on the bottom layer as a mode switching switch,realizing the switching between the reflection mode and the transmission mode of the structure.When the temperature control material vanadium dioxide is in the insulating state,the structure is in the transmission mode,and the structure can achieve a 150° phase dynamic adjustment by changing the Fermi level of graphene by external excitation.When the vanadium dioxide undergoes a reversible phase transition to a metallic state,the structure switches to a reflective mode,and the structure also achieves a 260° phase change by utilizing the change in the Fermi level of graphene.Through the research of this paper,the theoretical exploration of the modulation principle and performance optimization of different phase modulation devices is realized,and the design of various phase modulation devices is realized according to the research results.The proposed functional structure design of terahertz metamaterials can provide a new idea for different applications in various scenarios and the design of high-efficiency and intelligent terahertz devices.