Study On The Mechanism Of Graphene Plasmon-induced Absorption Effect And Its Application

With the rapid development of society,people have now entered a new era of high-speed informatization and big data,so traditional information technology can no longer meet people’s increasing requirements for digital information transmission.With the development of the field of information science and technology,high-speed integrated,small-size optical devices have gradually been used by people.These devices have made great progress in overcoming the optical diffraction limit.For example,optical devices based on surface plasmons can bind electromagnetic waves to metal surfaces and manipulate the transmission of electromagnetic waves at the nanometer scale.In general,once the optical structure supporting the transmission of plasmon on a metal surface is determined,its optical properties will hardly change unless the geometric parameters of the structure change.Therefore,how to achieve dynamic adjustment has attracted great attention from scientists.As a new type of special material,graphene provides us with a new way to realize the dynamic adjustment of the structure.This paper is based on the graphene plasmonic structure and uses the finite time-domain difference method to make in-depth research on plasmon-induced absorption.The work and conclusions of this paper are as follows:A novel structure composed of monolayer graphene,an Al₂O₃ isolated layer and a grooved silver is proposed.Plane incident light is perpendicularly incident on our structure and excites the quasi-waveguide mode of monolayer graphene and the Fabry-Perot resonance mode of silver trenches.Constructive interference between these two modes leads to plasmon-induced absorption.Numerical simulations revealed at least three advantages over our previous structure.First,the extinction ratio can reach⁹9.999%,resulting in the ultra-high figure of merit*（FOM*）as high as 10⁶.Second,the intensity of this pronounced PIA effect can be dynamically optimized by varying the coupling distance.Third,the resonance frequency can be easily tunable by varying the graphene Fermi level.This system may have potential applications in dynamically optical switching and biochemical sensing.Plasmon-induced absorption（PIA）in an ultra-compact graphene waveguide system which is composed of a single graphene sheet with two air cavities side-coupled to a graphene nanoribbon is shown.By designing two coherent optical pathways,the pronounced PIA can be achieved due to the extreme destructive interference between the radiant and subradiant modes supported by the two graphene nanoribbons.The resonant strength shows strong dependence on the coupling distance between the two graphene nanoribbons and the resonance wavelength can be dynamically tuned by varying their Fermi energy.Furthermore,the group delay time up to-0.14 ps can be reached at the PIA window,suggesting unique fast-light feature.In addition,the double PIA phenomenon is also analyzed by introducing another graphene nanoribbon.Our results may pave the way for controlling the transmission of a light signal in the design of ultracompact plasmonic devices.