Optical Sensor Based On Plasmon Resonance Coupling

Surface plasmons(SPs)are free electron gas masses that exist on the metal surface.When the incident light illuminates the metal surface,the free electron gas masses interact with the incident light to produce a special electromagnetic oscillation mode,which we call surface plasmons resonance(SPR).Because surface plasmon resonance has a series of unique optical characteristics such as breaking the diffraction limit and strong local field enhancement,the optical elements of the metal micro-nano structure are more miniaturized and integrated.These micro-nano structures are also widely used in surface enhanced Raman scattering,optical sensors,lasers,medical imaging and other fields.This thesis mainly studies optical sensors based on surface plasmon resonance coupling.Firstly,the research significance,development status and optical characteristics of surface plasmons are explained.Then,the physical mechanism of surface plasmon resonance is further understood through the classification of surface plasmon resonance,and several applications based on surface plasmon resonance are analyzed.A method to enhance surface plasmon resonance is proposed.Aiming at the application of surface plasmon resonance in optical sensors,according to the basic theory of electromagnetic field,this paper innovatively proposes two surface plasmon resonance coupling sensor structures with high sensing performance,and uses CST based on the finite element analysis method.The simulation software performs simulation calculations.1.We theoretically studied the optical properties of T-dimer(TD)nanostructures and T-dimer nanostructures(TD/NL)with nanowire loading(NL).By depositing NL around the TD nanostructure,the optical properties of TD have been significantly changed.The extinction spectrum of TD/NL shows a split resonance peak,and the asymmetry of Fano resonance due to plasmon hybridization is shown.In addition,stronger electric field enhancement can be obtained in the composite TD/NL nanostructure.The calculation results show that in the designed TD/NL nanostructure,the field enhancement effect of the dark mode is three times than the TD nanostructure.At the same time,the Fano resonance in the TD/NL nanostructure shows a narrow spectral linewidth and high quality factor,which is beneficial to optical refractive index sensors.By changing the refractive index of the surrounding environment of the structure,the measurement sensitivity is as high as 1083 nm/ RIU.2.We designed a new type of plasmon chip component deposited on a glass substrate based on surface plasmon resonance(SPR)for refractive index sensing.Ag is selected as the surface plasmon metal material,and its performance is numerically studied by the finite element method(FEM).In the near-infrared region,due to the resonant coupling between the plasmon nanostructures,the light absorption is significantly enhanced,while the scattering is weakened,forming an obvious groove.We apply it to the field of sensing,and the simulation results show that the average sensitivity of the proposed sensor is 669 nm/RIU when the refractive index varies from 1.332 to 1.467.Therefore,the sensor can effectively monitor subtle changes in the surrounding environment,and has great commercial value for biomedical and organic detection and related applications.