Absorption And Sensing Characteristics Of Narrow Band Light Based On Surface Plasmons

Surface plasmon（SP）is an electromagnetic mode formed by the interaction of free electrons and photons at the interface of metals and dielectrics.It can confining the electromagnetic field to a small extent on the metal surface and strengthens it.Surface plasmons can break through the diffraction limit and have strong local field enhancement characteristics,which can realize nanoscale optical information transmission and processing.In addition,the unique characteristics of surface plasmons make it widely used in the fields of highly sensitive biological detection,sensing and new light sources."Metamaterial"refers to composite materials that have artificially designed structures and exhibit extraordinary physical properties that natural materials do not have.Metamaterial have special properties that natural materials do not have,and these properties mainly come from artificial special structures.This paper mainly describes the simulation and result analysis of two different types of metamaterial narrowband absorption structures using the time-domain finite difference method FDTD,and optimizes the two structures to achieve the best performance.The content of this article is as follows:1.A design method of ultra-narrow band absorber platform using asymmetric silicon-based dimer resonator grating is proposed.In the infrared range of3000～4000nm,the absorber produces two narrowband absorption peaks with an absorption rate greater than 99%,and the half-height and full width at both absorption peaks are within 10nm.In addition,during optical sensing,the absorption wavelengths of this absorber platform atλ₁=3468 nm（S=3193 nm/RIU,FOM=532）andλ₂=3562 nm（S=3120 nm/RIU,FOM=390）show a high-performance sensitivity factor.Strong scattering coupling and the magnetic resonance supported in this silicon-based grating produce high absorption.And,using other methods,such as polarization and angle of incidence,to further adjust the absorption response of intensity and wavelength,demonstrates the feasibility of manual operation.2.A perfect narrowband absorber based on the"mountain"zigzag separation resonator is proposed,the enhanced magnetic dipole resonance is introduced,and its application potential in the field of optical sensing is analyzed.In this structure,the radiative damping of magnetic dipole resonance is almost completely suppressed,because the underlying metal can play a good role in suppressing light transmission,thereby strongly enhancing the field confinement in the spatial range.In addition,based on the asymmetric design in the introduced"mountain"shaped resonator,three nearly uniform absorption peaks are obtained,indicating the multi-channel operation of the light field.Finally,its potential applications in refractive index sensing are introduced.The open structure increases the contact area of the absorber with the outside and makes it easier to interact with the detection object,thus providing unique advantages in sensing.The two narrowband absorption structures proposed in this paper achieve perfect multi-frequency narrowband absorption and good sensing performance（high quality factor,high sensitivity）in the infrared wavelength range.These findings make these two absorber platforms have great potential in the field of sensing and inspection.Therefore,it has potential applications in the field of electronic information acquisition and the design of electronic equipment.