| Terahertz wave(THz)is located at the intersection of electronics and photonics.With its characteristics of low energy,wide spectrum,strong penetration and transient,THz has important applications in national defense,medical care,and communications.THz sensing technology,as the focus of THz application technology research,provides possibilities for THz spectrum technology,biomedical diagnosis and nondestructive testing.However,the low sensitivity of free space THz detection technology will limit its practical application range of sensing.Metamaterial is a periodic subwavelength metal or artificial composite materials composed of dielectric resonator,through the study of the design of the structure to achieve the required functionality,it can not only enhance the local electric field,also has the advantage of the advantage of being sensitive to the dielectric properties of the surrounding environment.Therefore,based on metamaterials,THz sensors will show great application value.In this paper,a series of researches based on metamaterial sensing have been carried out in THz band,and excellent sensing performance has been achieved by using the physical characteristics of annular dipole,anapole mode,electromagnetically induced transparency,etc.,and high tunability of sensitivity has been achieved by using graphene,and a continuous,multi-mode,flexible controlled terahertz metamaterial sensor has been proposed.The main work of this paper is as follows:1.A terahertz metamaterial device based on graphene and metal is proposed,which utilizes the excited Anapole mode to achieve high-quality factors,and combines the unique electromagnetic properties of graphene to achieve excellent tuning performance.When graphene is placed in the central gap of the structure,the resonant frequency is regulated by the destructive interference that affects the ring dipole and the electric dipole resonance,and the tuning capability is up to 250 GHz/0.1eV.When graphene is added to the gap on both sides of the metal structure,the magnetic quadrupole is significantly affected,and the tuning effect is also good.The high sensitivity of anapole mode and the tuning performance of graphene provide potential applications for reconfigurable metamaterial sensors.2.A method for active regulation of electromagnetically induced transparency metamaterials using graphene in fully dielectric materials is proposed.The electromagnetically induced transparent effect is realized through the structure composed of silicon ring and silicon rectangular rod resonator,and a single layer of graphene is integrated into the metamaterials to realize the active tuning function of multiple modes.When the graphene is placed below the silicon ring resonator and the Fermi energy level changes from 0 to 0.6 eV,the transmission peak of the resonance frequency of the device decays from 0.9 to 0.3.When the graphene is placed belw the silicon rod resonator and the Fermi level changes from 0 to 0.3 eV,the transmission peak modulation range of the resonance frequency of the device is 0.9 to 0.3.This multi-mode active tuning mode has good role value in slow light and optical switching.3.A terahertz device based on a novel hybrid metal-dielectric metamaterial is proposed to realize electromagnetically induced transparency effect.The anapole mode(dark mode)of the weak far-field radiation of the silicon disk in the terahertz band is excited by the local surface plasmon resonance generated by the metal structure as the bright mode.The destructive interference between the two modes occurred at 1.654 THz,and the electromagnetically induced transparency of high Q factor was realized.The refractive index sensing sensitivity of the device is up to 0.414 THz/RIU,and the effect of the resonance quality factor on the material geometric parameters is further studied,which provides a new way to realize electromagnetically induced transparency. |
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