Research On Modulation Characteristics Of Terahertz Based On Perovskite/Lithium Niobate And Plasma Induced Transparency

Terahertz modulation is one of the key technologies of terahertz communication.The research and development of high-performance terahertz wave modulation devices to achieve efficient manipulation of terahertz waves is an urgent problem that needs to be solved in the current development of terahertz communication technology.Combining the photoelectric response and transient response characteristics of ferroelectric materials,this paper is based on the theory of plasma-induced transparency,designed and studied terahertz metamaterial modulation devices based on lithium niobate and perovskite films.The main research contents are as follows:(1)The physical mechanism of plasma-induced transparency is explored,and the reason for plasma-induced transparency modulation is explained using the coupled Lorentz model.In addition,the theory of dielectric response of ferroelectric materials is explored,which provides a theoretical basis for the later analysis of the reason why the dielectric constant of lithium niobate changes under laser pumping.(2)The dielectric properties of lithium niobate and the modulation effect of the terahertz metamaterial prepared in a lithium niobate substrate pumped by a 1064 nm laser are studied.Experimental results show that as the pump light intensity increases,the transparent window of the modulator gradually decreases,and the maximum modulation at the transparent window reaches 27%.The coupled Lorentz model is used to analyze the reason for the reduction of the transparent window,which is mainly caused by the photothermal effect and iron polarization effect of lithium niobate.(3)The modulation characteristics of perovskite/lithium niobite and the modulation effect of the terahertz modulator based on the perovskite/metamaterial/lithium niobate pumped by a1064 nm laser are studied.Experimental results show that as the pump light intensity increases,the transparent window of the modulator gradually disappears,and the maximum modulation degree of the transparent window reaches 77%.Through the dielectric constant of lithium niobate and perovskite film,the reason for the disappearance of the transparent window is analyzed.The main reason is that the change of dielectric constant affects the coupling between the metamaterial structure.