Design Of Dynamically Tunable EIT Metasurface Based On Vanadium Dioxide

Due to its high security,strong spectral resolution and wide bandwidth,terahertz spectrum and technology have shown great development potential and broad application prospects in many aspects.Electromagnetic metamaterial is a new kind of artificial material which is different from natural material.The properties of metamaterials depend on their structure rather than on the materials of which they are composed,thus allowing a greater degree of freedom in the flexible modulation of the use of electromagnetic waves.Therefore,the design of terahertz devices using metamaterials is a favorable way to realize the utilization of terahertz band.Electromagnetic induced transparency is a quantum interference effect,which was first discovered in the field of physics,and its physical mechanism can be explained by the physical mechanism of three-level atomic system.Electronically induced transparency phenomenon has a unique advantage in designing optical memory,optical open light and slow light devices.Based on this,two different terahertz metamaterials tunable electromagnetically induced transparent devices are designed and their main properties are analyzed through research and analysis in this work.The main contributions are as follows:1.In this work,we have designed an electromagnetic induced transparency metasurface with dynamic tunable resonance strength based on Vanadium dioxide.The designed metasurface cell consists of a square quartz substrate,a gold cut-wire resonator(CWR),and a gold split-ring resonator(SRR).In order to achieve tunability,the phase transition characteristics of vanadium dioxide can be used to add a structure composed of vanadium dioxide to the original structure to change the coupling characteristics of the original structure.When vanadium dioxide is in the insulating phase,the vanadium dioxide strip at the openings of SRR does not participate in the resonance,and the CWR is coupled with the SRR,resulting in a transparent passband with a peak.With the increase of temperature,the conductivity of vanadium dioxide increases gradually.At the same time,the degree of participation of vanadium dioxide strip in the reaction increases,and the transparent window gradually disappears.Thus,using the transition of vanadium dioxide from insulating phase to metallic phase,the dynamic modulation of electromagnetic induced transparency resonance intensity and the group delay can be realized.And the modulation depth can reach 74.6%2.Based on the phase transition properties of vanadium dioxide,an EIT with metasurface is designed to adjust the frequency position of transparent window.The unit cell of the metasurface consists of a cut wire(CW)resonator embedded with vanadium dioxide and two C-shaped ring resonators.The simulations show that when vanadium dioxide is in the insulating phase,the electromagnetic induced transparency window appears at 0.58-0.74 THz.While vanadium dioxide is in the metallic phase,the electromagnetic induced transparency window is located at 0.37-0.50 THz.