Design Of Terahertz Metamaterial Modulator Based On The Transition Principle Of Vanadium Dioxide

Terahertz technology has received much attention due to its enormous potential for applications in wireless communications,spectroscopy,imaging and biomedical applications.In order to use THz waves in practical applications,terahertz filters,modulators,phase shifters,switches,which integrate the present and the benefits,have been developed.In order to overcome the limitations of the electromagnetic properties of natural materials in the THz band,artificially controlled electromagnetic properties of super materials have emerged.The design of different metamaterial unit structures provides unlimited possibilities for manually manipulating terahertz waves.As an ideal material for thermal control system,VO2 will undergo reversible phase transition from insulating phase to metal phase under temperature excitation.The phase transition time is short and controllable,and its excellent performance has received more and more attention.Therefore,it is of great significance to explore and explore the properties and applications of artificially adjustable terahertz metamaterials based on the principle of VO2 phase transition.In this paper,the active control of terahertz waves is realized by combining metal and VO2 into different periodic patterns.The control method is flexible and diverse,and the main work is as follows:(1)Different patterned structures are etched through the metal surface.It shows the process of increasing the resonant frequency of the modulator from one to four.The dynamic regulation of the amplitude of the terahertz wave is realized.Finally,the four-frequency point modulator has absolute modulation depths of 0.82,0.66,0.85,and 0.64 at 0.31 THz,0.54THz,0.77THz,and 1THz.The absolute modulation depth is demonstrated to be a measure of the rationality of the modulator’s performance.The surface current surface electric field diagram is used to explain the mechanism of resonance and the cause of the change of the resonance frequency.Finally,the resonance characteristics of the quad-band modulator are stable when the incident angleφ changes from 0° to 30°.(2)Design of two dual-frequency tunable modulators through a "T" shape and a split resonant ring.When the electric field is polarized along the Y-axis,the "T"-shaped modulator resonance point before and after the VO2 phase change moves from 3.84THz to 3.6THz and 4.29THz.The phase change is up to 68 °.The split resonant ring modulator resonance point was shifted from 3.48THz and 4.05THz to 3.82THz and 4.49THz.The phase change is up to 100°.When the electric field is polarized along the X-axis,the"T"-shaped modulator resonance point before and after the VO2 phase change moves from 3.67THz and 4.45 to 3.77THz.The phase change is up to 112°.The split resonant ring transmission is not affected by the polarization of the electric field,and the resonance characteristics are unchanged.The variation of the resonant frequency and the electromagnetic response are explained by the surface electric field current.The characteristics of the base size increasing the red shift of the resonance point are analyzed.The designed split resonant ring maintains a constant resonant characteristic of the incident angle φ over a range of 90°.(3)The PIT effect is realized based on the near-field coupling theory by means of strip VO2 and metal strips arranged in different ways.The formation cause and formation mechanism of the PIT-based modulator are analyzed.The effect of coupling distance variation on the modulator and its application in sensing and slow light.The sensing sensitivity is 1.092THz/RIU.The group delay is 2.7 ps in slow light.By temperature-controlled VO2 metamaterial,both the amplitude modulation of the transparent window and the resonance frequency shift of the transmission valley are realized.Before and after the phase change,the resonance point moves from 3.18THz and 3.45THz to 2.9THz and 3.45THz,and the absolute modulation depths at 0.58THz,3.12THz,3.18THz,3.29THz,3.33THz,3.45THz are 0.55,0.51,0.7,0.5,0.62,0.68.The proposed metamaterial structure offers more possibilities for the design of tunable devices,slow-light devices,sensors,switches,and the like.