Study On Terahertz Wave Amplitude And Spectrum Control Devices Based On Vanadium Dioxide Metamaterials

Terahertz technology has a very important application prospect in the fields of broadband communication,airport security,biomedicine and high sensitivity sensing.Currently,the lack of effective terahertz functional devices has become the bottleneck of the rapid development of terahertz technology.Metamaterials,also known as artificial electromagnetic materials,can be used to design novel terahertz functional devices to achieve effective regulation of terahertz waves.Therefore,in recent years,more and more attention has been paid to terahertz functional devices based on metamaterials.In this context,this paper studies the terahertz wave amplitude and spectrum regulation technology based on vanadium dioxide metamaterials.The main contents are as follows:1.We study the transmission theory of typical terahertz metamaterials and the design method of terahertz functional devices based on metamaterials.The characteristics and phase transition theory of VO₂,the key material in this paper,are introduced.On this basis,the processing technology of terahertz functional devices based on vanadium dioxide metamaterials is studied.2.We design and manufacture a terahertz amplitude control device based on vanadium dioxide metamaterials.The upper cell structure of the amplitude control device is composed of two symmetrical cross resonators and a monotype center bar.The transmission spectrum of a terahertz amplitude control device with VO₂ of different conductivity is simulated with CST software.The performance of the sample is characterized using the terahertz time-domain spectral system to test.In the power-on test experiment,when the applied current increases to 0.27A,the maximum modulation depth of the terahertz amplitude control device reaches 96%.Meanwhile,hysteresis effect and backstroke error of VO₂ in the phase transition are measured.The test results show that the designed terahertz amplitude control device has very small hysteresis effect.In order to optimize the structure of the device,the surface current profile is used to study the causes of the variation of the upper cutoff frequency and the effect of the geometrical parameters of the element structure on the upper cutoff frequency.The results show that changing the structural parameters of the element can change the upper limit cutoff frequency of the terahertz amplitude regulator.3.We design a terahertz spectral control device based on vanadium dioxide metamaterials.The upper cell structure of the spectral control device consists of metal aluminum ohmic ring?OR₁?,circular open-end ring?SRR₁?of VO₂ material and circular open-end ring?SRR₂?of metal aluminum from the outside to the inside.Simulation results show that changing the conductivity of VO₂ material can regulate the terahertz wave transmission rate.When the conductivity of VO₂ increases,the transmission rate at the central frequency of 0.77THz decreases from the maximum value of about 0.76 to the minimum value of 0.01,reaching more than 98%of the modulation depth.However,the two resonance peaks at the low frequency 0.58THz and the upper limit cut-off frequency0.94THz disappeared,leaving one single resonance peak at the central frequency.Thus,the conversion from transmission to reflection is successfully realized in this frequency band.In order to optimize the parameters of the element structure,the influence of the thickness of the element structure on the terahertz wave transmittance and the influence of the opening width on the resonance peak are analyzed.The research results of this paper provide a new idea for the research and development of new terahertz functional devices,which is of great significance for promoting the development of terahertz technology.