Design Of Surface Plasmon Nanostructures And Their Sensing Properties

The application research of surface plasmons has always played an important role in the fields of biology,chemistry,materials,medicine,and energy.Among them,the application of surface plasmon resonance in sensors has always been a hot research direction.The focus of sensor application research is on the improvement of sensing performance.In this paper,by studying the coupling of localized surface plasmon resonance with dielectric waveguide mode and the metal-substrate-enhanced magnetic dipole resonance in metamaterials,biosensors with high sensitivity are obtained,it is of great significance to study the application of sensors based on surface plasmon resonance.This thesis firstly explains the basic theory of surface plasmon and introduces localized surface plasmons,surface plasmon polariton and some applications of surface plasmons.Secondly,the surface plasmon metal nanostructure sensors and electromagnetic calculation and simulation method are introduced.Finally,this thesis innovatively proposes two designs for biosensor chips based on surface plasmon resonance.The content of this thesis mainly includes the following two aspects:1.We show a high-performance refractive index(RI)sensor,which consists of a two-dimensional(2D)gold nanoparticle array lying on a dielectric slab waveguide.The sensor has high RI sensitivity and figure of merit(FOM),reaching 250 nm/RIU and 28,respectively.Such a high RI sensitivity and FOM result from a sharp Fanolike resonance,which is caused by the interference between the localized surface plasmon resonances(LSPRs)excited on individual gold nanoparticles and the waveguide mode propagating in the adjacent dielectric slab.The interference condition is that the electric field of the waveguide mode must be parallel to the polarization direction of the LSPRs.Our work may have potential applications in ultra-compact biomedical sensing.2.We investigate metal-substrate-enhanced magnetic dipole resonance in metamaterials for high-performance refractive index sensing.The metamaterials are composed of periodic arrays of vertical U-shaped split-ring resonators,dielectric spacer,and metal substrate.Because the metal substrate blocks the transmission channel of light,the radiative damping of magnetic dipole resonance is nearly completely suppressed and thus its quality factor is increased noticeably.Owing to the narrow bandwidth,nearly-zero reflectance,and huge enhancement of electromagnetic fields at the magnetic dipole resonance,our designed metamaterial sensor has very high sensitivity(S = 1308 nm/RIU,S* = 26/RIU)and figure of merit(FOM = 52,FOM* = 1187).The good sensing capability allows for a much more sensitive detection of small refractive index changes and suggests potential applications in biosensing.