Research On Terahertz Functional Devices Based On Metamaterials

With the rapid development of communication technology and computer science,the frequency band resources in the communication band and microwave band are gradually scarce,and it is difficult to continue to improve the transmission efficiency of information.Therefore,the need to develop high-frequency bands is imminent.Terahertz waves are located in the transition range between electronics and photonics,and have great development potential and application prospects due to their strong penetrability and low photon energy.However,it is difficult for traditional semiconductor materials to maintain high performance at high frequency and high speed.The combination of metal metamaterial structure design and active materials can achieve dynamic regulation in the terahertz band,opening up high-performance terahertz functional devices.a new path.First,this paper proposes a terahertz modulator based on the hybrid structure of graphene and metal metamaterials.The device adopts a metamaterial structural unit composed of a double strip metal and a regular hexagonal open ring,and covers a layer of graphene on the regular hexagonal open ring,and controls the Fermi energy of graphene by applying a gate voltage.The size of the stage leads to the energy transfer between the light-dark mode resonant units and the shift of the transmission peak and the change of the amplitude,so as to achieve the modulation of the resonant frequency and intensity of the resonant unit and realize the dynamic adjustability of the structure.The simulation results show that the device can achieve an insertion loss of 0.40 d B,a modulation depth of 99.99%,an extinction ratio of 42.17 d B and a group delay of 11.2ps when the operating frequency is 2.693 THz.Its high extinction ratio,large modulation depth and simple structure are expected to be applied to future terahertz communication systems.First,this paper proposes a terahertz modulator based on the hybrid structure of graphene and metal metamaterials.The device adopts a metamaterial structural unit composed of a double strip metal and a regular hexagonal open ring,and covers a layer of graphene on the regular hexagonal open ring,and controls the Fermi energy of graphene by applying a gate voltage.The size of the stage leads to the energy transfer between the light-dark mode resonant units and the shift of the transmission peak and the change of the amplitude,so as to achieve the modulation of the resonant frequency and intensity of the resonant unit and realize the dynamic adjustability of the structure.The simulation results show that the device can achieve an insertion loss of 0.40 d B,a modulation depth of 99.99%,an extinction ratio of 42.17 d B and a group delay of 11.2ps when the operating frequency is 2.693 THz.Its high extinction ratio,large modulation depth and simple structure are expected to be applied to future terahertz communication systems.Subsequently,this paper proposes two liquid crystal-based metamaterial multilayer structure terahertz phase shifters.Both of these devices adopt a "sandwich" structure of metal resonant layerliquid crystal layer-metal layer,dividing the liquid crystal layer into an infinite number of locally small regions,and using a directional model to approximate the deflection angle of the liquid crystal molecules,while different deflections The director of the angle can calculate the equivalent permittivity in this state,thus realizing the phase shift.The results show that the first structure designed in this paper can achieve a phase shift of more than 352° in the frequency range of1.3552THz-1.3664 THz(with a bandwidth of 11.2GHz),and the insertion loss is 1.082 d B;(Bandwidth is 8.1GHz)The phase shift in the frequency range is greater than 352°,and the insertion loss is 0.35 d B.The problems of large loss,uncontrollable and small phase shift of the existing terahertz phase shifter are solved,and the two devices have good performance and simple structure,and work stably in the terahertz band.It is expected to have broad application prospects in the fields of terahertz wave radar,phased array antenna,communication and sensing.