Study On Sensors Based On Graphene Plasmon Induced Transparency

The transmission spectrum is extremely sensitive to the change of refractive index of medium,due to plasmon induced transparency(PIT)can produce a strong localized energy.It is very potential for PIT to be used in environmental detection,medical drug detection,food safety and biological detection,which has attracted the interest of many researchers.But due to the complexity of the structure,low sensing performance,and no dynamic tunability,the large scale applications of plasmon sensors are still challenging.Graphene is a novel,two-dimensional material.Not only it has metal-like optical properties in the terahertz band,but also it’s Fermi level can be changed by applying an electric or magnetic field.H ence,graphene has has become one of the most potential materials for the excitation of surface plasmon.In this paper,finite d ifference ti me domain method(FDTD)is used to design and optimizate graphene based PIT medium sensors.Simple structure,high performance,and dynamically adjustable sensors are designed by us.By couple-mode theory(CMT),the coupling process and mechanism of single PIT and double PIT are analyzed,respectively.The main innovation achievements of this paper are as follows:1.A simple dual-layer graphene metamaterial is proposed.The mechanism of single-PIT is analyzed by FDTD simulation and CMT theory.The results indicate that the induced transparency windows and performance of the structure can be controlled by changing Fermi energy level and geometry size.What is more,as a sensor,the structure has a high sensitivity of 15739 nm/RIU and a maximum figure of merit(FOM)of 469.The current work may pave the way for the further research on the applications and designs of nanosensors used in highly integrated optical circuits.2.Dual plasmon-induced transparency(PIT)is realized in the simple multilayer structure consisting three graphene layers.The coupling mechanism between the three modes of three graphene layers is analyzed in detail by analog electromagnetic induction transparency(EIT)and coupling mode theory(CMT).It is found the dual-PIT expresses dynamic tunability by tuning applied bias voltage.Moreover,proposed structure can be applied in the biosensor,and significantly improved sensitivity and figure of merit(FOM)as high as 16660nm/RIU and 31.0924 have been obtained.This work has potential applications in dielectric sensors and optical modulators.There are 36 figures,2 tables,and 121 citations in this thesis.