Research On Multiband Structure For Surface Plasmon Resonance Sensor

Surface plasmon resonance is a kind of physical phenomenon which is generated by free electron oscillating on metal surface,when proper light radiates to the interface of metal and medium.It can produce a strong local electric field,which is very sensitive to changes in the surrounding environment.Therefore,it has been widely used in highly sensitive biological and chemical sensors.With in-deep research of SPR sensing technology in different fields,local surface plasmon resonance(LSPR)sensing technology using metal nanoparticles or nanoparticle arrays has become an important research direction of SPR sensor.In this thesis,we aimed at the question of traditional surface plasmon resonance sensor usually works in single formant peak mode within the scope of the work frequency,cannot be suitable for multi-band,multi-channel sensing detection environment.First,puts forward a kind of embedded rhombic gold nanoparticles array,and then analyses the reasons why it can work in multiband,finally,the periodic array structure is applied to the SPR sensor,and the sensor performance of the structure is analyzed.The main contents are as follows:1.Based on the eigenvalue equation and finite-difference time-domain(FDTD)algorithm,the surface plasmon resonance sensing characteristics of rhombic gold nanoparticle arrays embedded in silica substrate are investigated,and the relationship between the resonance mode and embedded depth is derived.The calculated results agree with the numerical simulation,which show that the asymmetry of the upper and lower media of gold nanoparticle arrays can be equivalent to monolayer dielectric grating.The physical mechanism and influence factors of generating multiple resonance peaks in the transmission spectra are analyzed theoretically,which can provide a theoretical basis for the design of multi-band surface plasmon resonance(SPR)sensor substrate.2.On the basis of the above research,the effects of embedding depth,length-to-axis ratio and period size on the transmission spectrum are discussed.Meanwhile,the sensing characteristics of the structure are analyzed.From the simulation data,we can see that the SPR sensing structure based on the embedded rhombic gold nanoparticles has superior performance.The corresponding refractive index sensitivity of the three resonant peaks is 525.0nm/RIU,428.8 nm/RIU and 262.5 nm/RIU under the given structural parameters,respectively,and the FOM were 33.4,32.2 and 64.0.All of them satisfied to the performance requirements of conventional SPR sensors.