Study On Plasmon-Induced Transparency Phenomenon And Application Based On Graphene Metamaterials

Plasmon induced transparency(PIT)is a counterpart of classic electromagnetically induced transparency(EIT).Due to its strong dispersion effect in induced transparent windows,it has a wide application prospect in the field of nano optics.Graphene metamaterials have the advantages such as electrical adjustability,ultra-high carrier mobility,ultra-fast nonlinear optical response,etc.Therefore,the PIT effect based on graphene metamaterials has important guiding significance in the design of multifunctional optoelectronic devices.In this paper,multiple PIT effects were implemented by designing the structure of graphene metamaterials.Finite-difference time-domain(FDTD)and coupled mode theory,(CMT)are used to study its application in slow light,sensing and optical switches.The main content of the paper is as follows:A single-layer patterned graphene metamaterial structure composed of four identical large graphene blocks,two identical small graphene blocks and two identical graphene strips is designed to achieve the triple-PIT effect under the excitation of polarized light.A blue-shifted transmission spectrum can be obtained by changing the Fermi level of graphene.The maximum sensitivity and FOM are respectively 5.7115 THz /RIU(18350nm/RIU)and 116.32 by changing the surrounding refractive index.Finally,the slow light effect at different Fermi levels was studied.It can be found that when the Fermi level of graphene is 1.0 e V,the maximum group refractive index can reach up to 1036.Therefore,the proposed structure provides a new idea for the research of sensors and slow light devices.A double-layer graphene terahertz metamaterial-structure consisting of double graphene bands and double graphene rings is proposed to achieve a dynamically tunable triple-PIT.The simulated transmission spectra obtained by FDTD are in good agreement with the theoretical results obtained by CMT.This structure realizes a penta-frequency switching modulator according to the dynamically adjustable triple-PIT effect.The maximum modulation depth and the minimum insertion loss of the switch are 99.97%and 0.33 d B,respectively.In addition,the slow-light effect of the proposed structure is also further investigated by the time delay.The results show that when the Fermi level of graphene reaches 1.2 e V,the maximum time delay can reach 0.848 ps,and the biggest DBP is up to 0.58.Consequently,the proposed structure opens up a new idea for the research of multi-frequency optical switches and excellent slow-light devices.