Study On The Graphene Plasmon Induced Transparency And Its Application For The Regulation Of Terahertz Waves

In recent years,researchers have conducted in-depth research on the plasmon-induced-transparency(PIT)effect of graphene materials and the use of this effect to regulate terahertz waves,but there are still many problems like low regulation efficiency,poor modulation effect and complex design structure.The plasmon-induced-transparency can be achieved by the coupling of bright-dark mode and bright-bright mode,which has many excellent characteristics such as high transmittance at transparent window,slow-light,and the like.Using these characteristics,many optoelectronic functional devices can be designed.These optoelectronic devices have good control effects on light waves,microwaves,terahertz waves,and so on.Graphene is a typical two-dimensional crystal material.Among its many excellent optical and electrical properties,the most prominent is that the conductivity of graphene can be regulated by applying a bias voltage or an external magnetic field.The dynamic tunable nature of this conductivity makes the advantage of graphene-based functional devices very prominent,and thus has become a research hotspot.We hope to use the graphene plasmon to induce the transparency effect and its various characteristics,dynamically regulate the terahertz wave,and solve some problems in the previous research.The main contents of this dissertation are as follows:Characteristics of plasmon resonance is investigated,which is supported by horizontal and vertical notches in Graphene layer.PIT is realized through coupling of notches,in adddition obvious and sharp transparency window is observed in transmission spectrum.Effects,resulting from the change of varous geometric parameters,on PIT are studied.At specific frequency,transmission is monitored,through tuning the chemical potential of Graphene properly,step change of transmission from maximum to minimum is obtained.Thus active tunability of the condition for THz wave from on-state to off-state is realized.The dipole resonance characteristics of graphene strips were studied.Graphene strips with different lengths were placed on the upper and lower layers of the base material.The difference in dipole resonance frequency of graphene strips with different lengths was used to couple them in the near field,which produces an induced transparent window.By monitoring the phase change at the location of the transparent window,the value of the corresponding group delay is calculated using the formula.Simultaneously increase the chemical potential of the upper and lower layers of graphene,so that the position of the transparent window moves,and the frequency modulation of slow light is realized.Increasing the chemical potential of the upper graphene while reducing the chemical potential of the lower graphene keeps the position of the transparent window and the transmittance constant,realizing the amplitude modulation of slow light.Induced transparency was achieved in the annular slot graphene metamaterial,and the effect of the groove width and the change in graphene chemical potential on the transparency window was analyzed.By using the characteristics of plasmon resonance sensitive to the refractive index of the contact environment,the analysis layer is applied and its refractive index is changed,and the movement law of the transparent window is observed,thereby realizing the refractive index sensing.By precisely adjusting the chemical potential of graphene,the resonant frequency of the transparent window and the intrinsic resonance frequency of the biological structure are coincident,and the measurement accuracy and sensitivity are further improved in actual measurement.