Study Of Superresolution Focusing Based On Surface Plasmon

In recent years,the research of nanostructures based on surface plasmon poloritons?SPP?has attracted many researchers'attention.As a new nanoscale structure,this structure has a lot of specific optical properties and has been widely used in many fields.The generation of surface plasmon is mainly based on the interaction process of electromagnetic radiation and conduction electrons in metal interface or small metal structure.This interaction will lead to optical near field enhancement in sub wavelength region.The effective use of this characteristic has aroused the attention of many scholars.The resolution of ordinary optical microscope is limited by the diffraction limit,and the ultimate resolution?₀/2 has long been unable to satisfy the needs of modern scientific research.Although Kingsley later invented the immersion microscope in 1983,the resolution was further reduced to?₀/2n.However,due to the limits of the range of dielectric refractive index n,the resolution is still limited.If we can reasonably apply the enhancement effect of the high spatial frequency caused by the nano structure to the optical microscope,it is hopeful to further improve the imaging resolution of the optical microscope to the nanometer scale.This article first outlines the traditional microscope,which indicates the key to limiting its resolution.Then compare them with the high-resolution near-field microscope,and we find out that SPP can be combined to microscope to improve resolution by comparing their differences.Then we analyze the theory of SPP briefly.According to the numerical method,a new metal nanoscale array structure be designed to stimulate the SPP wave.The near field optical microscope is used to make a near field optical characterization of the designed structure,and the result of the characterization is in agreement with the theoretical analysis.Finally,as one of the practical examples of the structure,the biochemical sensing experiment has been completed.This article is composed of two important parts.The first is to make a simulation analysis of the designed structure that can stimulate and converge SPP wave.The simulation results under various condition parameters and the result of the simulation data processing are given.The optimal parameters are obtained by comparing the results.The simulation results show the hot spot effect?hot-spots?of the local enhanced field produced by the convergence of SPP in the tip of the micro nanostructure.The simulation results show that the hot spot effect?hot-spots?of the local enhancement field generated by SPP converging at the tip of micro nano structure reaches the nanoscale size,which is consistent with the theoretical conjecture.Two,the near-field measurement results further confirm that there will be a lot of small bright spots at the tip of the metal array structure,that is the"hot spot effect"proposed theoretically,which is consistent with the simulation results.Therefore,it is feasible to apply the small bright spot on the structure as the second light source?i.e.,nanoscale light source?to further enhance the resolution of the microscope.The structure not only shows the specificity of the optical properties,but also plays the role of the sensor in the detection of the biological reagent.In view of the limitations of the current experimental conditions,the biological sensing function of the structure has been verified by the absorption spectra measured by a spectrometer.The application results show that this structure can indeed play its unique role in biological sensing.