The Properties And Applications Of Multiple Plasmon-induced Transparency On Graphene-based Microstructure

Since Gordon Moore put forward Moore’s law in 1965,57 years have passed,and the development of traditional electronic chips has become closer and closer to its bottleneck.Photonic chip and related technology industries have brought new development and breakthroughs in terms of size,information transmission speed and capacity,anti-interference ability and so on.However,the new photonic technology must be compatible with the traditional electronic technology.In order to solve the problem of device matching at the interface of the two technical means,surface plasmon optics has been proposed.From the discovery of "wood anomaly" in 1902 to the introduction of the concepts of "metal plasma" in1957 and " Surface Plasma Oscillations" in 1960,the research framework of the whole field has been formed.Finally,in 2003,William L.Barnes discussed in Nature that the surface plasmon polaritons(SPPs)can break through the diffraction limit and has the characteristics of localized interfacial field,marking the birth of "Surface Plasmonics ".In this paper,regarding Plasmon-induced transparency(PIT)as the main research object,we focus on the multiple Plasmon-induced transparency(Multi-PIT)and the response characteristics of microstructure to the polarization state of incident light based on the SPPs excited by graphene microstructure.The simulation experiment is carried out by using the Finite-difference time-domain(FDTD),and the simulation results are theoretically analyzed and fitted by using coupled mode theory(CMT).Finally,the theoretical analysis of Multi-PIT-based micro-nano optical application is realized,the polarization response of graphene microstructure is described in detail,and the response mechanism model is established.The main research contents are as follows:Firstly,the Multi-PIT and its applications on multi-layer graphene microstructure.1.Based on the multi-layer graphene microstructure,dual plasmon-induced transparency(Dual-PIT)are realized and electro-optical switch is designed by the modulation of graphene Fermi level.According to calculation,the extinction ratio(ER)of the optical switch is 7.77 d B,the amplitude modulation can reach 83.3%,and the insertion loss in the “on” state is 7.2%.Moreover,the independent frequency modulation at three resonant frequencies is realized by adjusting the Fermi level within graphene of different layers.The frequency modulations are8.0%,7.4% and 11.7% corresponding to three resonant points.Therefore,this work provides the possibility for the application of electro-optical switch,frequency modulator and so on.2.The dynamically adjustable triple plasmon-induced transparency(Triple-PIT)phenomenon is simulated and realized by constructing graphene microstructure with double rectangle,vertical single rectangle,vertical double rectangle,and single rectangle.Based on this phenomenon and the modulation of graphene Fermi level,the Synergistic Effect,a Single-PIT(Single plasmon-induced transparency)can evolve to Triple-PIT and then the Triple-PIT can change into Dual-PIT with the increase of modulation phase,is found in the Triple-PIT of graphene microstructure.In addition,this Triple-PIT can be applied to realize multi-frequency simultaneous optical switch by adjusting different Fermi levels.The amplitude modulation at four resonant frequencies are 74.7%,87.8%,76.5%,and 77.7%,respectively.This work has important reference value for the formation and interpretation of Multi-PIT,and provides theoretical support for the application of simultaneous optical switch.Secondly,the response of Multi-PIT to polarization state of incident light.1.A polarization sensitive graphene microstructure composed of four graphene strips and four graphene blocks is designed.Synchronous and asynchronous optical switching effects are realized by adjusting the Fermi level within graphene.The modulation degrees are 77.7%,58.9%,75.4%,and 77.6% at 2.059 THz,2.865 THz,3.381 THz and 3.878 THz,respectively.Moreover,It is found that the phenomenon of "polarized light affecting microstructure" can realize "selective transmittance of microstructure to linearly polarized light" in turn.Based on this,the application of tunable polarizer is proposed,the polarization extinction ratios(PER)are 4.2 d B,7.8 d B and 12.5 d B respectively.This work provides theoretical support for the research of polarization sensitive metamaterials and SPPs-based polarizers.2.An optical switch is proposed,which is insensitive to incoming polarized light.Firstly,the Triple-PIT is realized in the single-layer microstructure composed of graphene strip and graphene square ring.Then the graphene microstructure is insensitive to polarized light by the independent research and polar coordinate analysis to each microstructure.In the cases of x-polarized light,y-polarized light,and even left and right circularly polarized light,the Triple-PIT is equivalent.Therefore,the realized optical switch is also effective for polarized light in any direction,here,its modulation degrees of amplitude corresponding to 1.905 THz,2.455 THz,3.131 THz,and 4.923 THz are 90.1%,80.1%,94.5%,and 84.7%,respectively.Thus,this work is of great significance for the application of polarization insensitive optical switch.3.Combined with the relative study of PIT-based devices with "polarization sensitive" and "polarization insensitive",It is found that the response of polarization-sensitive graphene strips to the polarization state of incident light satisfies the Boltzmann function.In the proposed quadruple plasmon-induced transparency(Quadruple-PIT)microstructure,when two graphene strips exist at the same time,the sum of transmission is a constant under the action of this Boltzmann function.In this time,the property of conjugate change of the two strips is the reason for polarization insensitivity.In addition,the n-order CMT for fitting Multi-PIT phenomena are calculated,which greatly simplifies the operation steps,and solves the problem of repeatedly calculating the low-dimensional CMT when calculating the specific dimensional CMT each time.Moreover,when n = 5,it fits well with the Quadruple-PIT of FDTD.This work provides an important theoretical support for the study of polarization response of graphene microstructure.