Design Of Terahertz Waveguide Modulator Based On Double Graphene Structure

With the rapid development of terahertz technology,terahertz modulator has been paid more and more attention as an indispensable device in terahertz communication technology.From the initial exploratory realization of terahertz wave modulation,researchers now on the terahertz modulator specifications are already high modulation depth,high modulation rate.In this paper,a waveguide type terahertz modulator based on double graphene structure is designed and fabricated,which has the potential to realize high modulation rate and high modulation depth.The graphene material has excellent electrical conductivity and high electron mobility.In this paper,a five-layer structure of silicon-graphene-insulator-graphene-silicon is designed,and the insulating layer is alumina.The theoretical calculation shows that the applied voltage of the graphene on the upper and lower layers can change the conductivity of graphene,then affect the dielectric constant.The terahertz wave is incident parallel to the surface of the graphene.When the applied voltage is different,the dielectric constant of the graphene material is not the same,and the graphene's absorption effect of the terahertz wave is also different.The general rule is that the stronger the applied voltage,the stronger the absorption of terahertz wave.Thus,the modulation effect on the terahertz wave is realized at different applied voltages.In the experimental measurement,the waveguide modulator samples were measured by the terahertz time-domain spectroscopy system and the Gunn tube system,respectively.The final measurement of a maximum modulation depth of 85%.By theoretical analysis,the design model of the ideal case of the modulation rate is 500MHz.