Research On Tunable Terahertz Phase Shifter Based On Liquid Crystal/Vanadium Dioxide

With the rapid development of terahertz technology,the terahertz phase shifter,as one of the terahertz control devices,has become a research hotspot.The existing phase shifters have the disadvantages of large size and small phase shift.Based on the characteristics of tunable dielectric constant of electronically controlled liquid crystal and tunable conductivity of temperature controlled vanadium dioxide,three types of liquid crystal+silicon/metal composite structure terahertz phase shifters and two kinds of vanadium dioxide+metal composite structure terahertz phase shifters have been designed successively.A terahertz phase shifter with a liquid crystal-grating composite structure is proposed.The phase shifter consists of a quartz layer,a graphene layer,a liquid crystal,a grating structure,a graphene layer and a quartz layer from top to bottom.Using the anisotropy of the liquid crystal material,by changing the voltage applied to the graphene electrode,the dielectric constant of the liquid crystal is changed,so that the phase of the entire device moves due to the change of the dielectric constant,and the effective adjustment of the phase in the terahertz band is achieved.The research results show that the terahertz phase shifter achieves a phase shift of 400° in the range of 0.39THz?0.46THz,and the return loss is within-11dB.The maximum phase shift reaches 4220 at f=0.43THz.Moreover,the terahertz phase shifter is insensitive to polarization within an incident angle of 0° to 30°,and has the advantages of large phase shift and miniaturization.A terahertz phase shifter with a liquid crystal-metal four-right-angle composite structure is proposed.The designed phase shifter is composed of a metal copper layer,a graphene layer,a liquid crystal,a quartz layer,and a graphene layer in order from top to bottom.The layer constructs four right angle structures.With no external electric field(??=2.47)and an external electric field(??=3.26),the phase shifter can achieve a maximum phase shift of 350.58° at f=1.91THz,and further combined with the current energy density map.The surface current diagram explains the shifting mechanism of the proposed phase shifter.A double-layer liquid crystal-metal composite structure terahertz phase shifter is designed.The device consists of a copper electrode layer,a liquid crystal layer,a copper electrode layer,a quartz layer,a copper electrode layer,a liquid crystal layer,a copper electrode layer.The quartz layer is arranged from top to bottom,and the fishing-net structure is constructed on the top layer of metallic copper,and the ?shape+double right angle combination structure is constructed on the middle metallic copper electrode layer.The phase shifter has a three-band phase shifting effect in the 0.4-3THz frequency band,and the maximum phase shift amounts are 248.4°,102.4°,and 338.4°,respectively,and can be achieved in the 2.31THz-2.48THz(bandwidth 160GHz)frequency band.The amount of phase shift above 330°.At an incident angle of 15°,the phase shifter has a four-band phase-shifting effect,reaching maximum phase shift amounts of 322.4°,122.7°,253.7°,and 101.2°,respectively.A terahertz phase shifter with vanadium dioxide embedded in a metal ring composite structure is proposed,which consists of a copper layer,a vanadium dioxide layer,a liquid crystal layer,a copper layer,a vanadium dioxide layer,and a silicon dioxide layer from top to bottom.A rectangular notch structure is constructed on the upper metallic copper layer,a double rectangular structure is constructed on the upper vanadium dioxide layer,and a U-shaped structure is constructed on the lower metallic copper layer and the lower vanadium dioxide layer,respectively.The research results show that the maximum phase shift is 355.37° at f=0.736THz,and the phase shifts that can be achieved in the range of 0.732?0.749THz(bandwidth 16GHz)all exceed 350°.In the frequency range of 0.8?1.2THz,the proposed phase shifter can maintain nearly 80%transmittance.A vanadium dioxide notched rectangular+rectangular metal composite structure terahertz phase shifter is proposed,which is composed of a copper layer,a liquid crystal layer,a vanadium dioxide layer,and a silicon dioxide base layer from top to bottom,and the metal copper layer is rectangular.The structure is composed of a circular notch on the vanadium dioxide layer.In the range of 1.28THz?1.6THz(bandwidth 0.32THz),the phase shift of more than 230° can be achieved,and the maximum phase shift of 244.76° can be reached at f=1.59THz.The proposed five phase shifters all have the advantages of simple structure,miniaturization,flexible adjustment,and all have large phase shifts and broad application prospects in terahertz systems.