Properties Of Surface Plasmon Polaritons And Enhanced Fluorescence Applications Based On Metallic Nanostructures

In recent years,in the field of nanophotonics,unique optical properties of metallic nanostructures contribute to optical communication and light manipulation in a variety of researches.Surface plasmons are the manifestations and means to realize the optical properties of these micro-nanostructures.However,the loss resulting from the intrinsic resistance in the metal deteriorates the performance of nanodevices which depend on the long-distance propagation of surface plasmons,and thus low loss devices and materials have become main goals in the field of nanophotonics.Additionally,many studies avoid the propagation of surface plasmon,more inclined to use the structure of light concentration instead,that is,local surface plasmons study.In the applications of the relative light-matter control researches,metallic metasurfaces have also made remarkable achievements,while for the application of active structures more researches need to be conducted.Based on the above considerations,this paper proposes to excite and control the propagation of surface plasmons on the low loss metallic nanostructures,and to control the fluorescence emission enhancement by using the split-ring-resonator based metasurface with rich electric and magnetic resonances.The full text revolves around the following aspects:For propagating surface plasmons,the non-destructive leakage radiation microscopy method is introduced to detect the propagating properties in single-crystalline gold nanoplates(length 10?20 ?m,thickness 30 nm).At the same time,both the real image and Fourier image are used to characterize and control the propagation of leaky modes.The surface plasmons on gold nanoplates of different shapes(triangle and hexagon)are analyzed theoretically,and the propagation constants and propagation directions are obtained in the experiments.The simulation results are in good agreement with the experiment results.By changing the position and the polarization of the incident light,the intensity and propagation directions of the leaky modes can be obtained.For the metallic metasurfaces applied in local surface plasmons,we utilize the gold split-ring-resonator(SRR)based metasurface with promising magnetic resonances which are favorable to weakening fluorescence quenching.At oblique incidence,both x-and y-polarized excitation can excite the magnetic modes to enhance the fluorescence.For x-polarized incidence,the fluorescence is enhanced by a factor of 18 because of the magnetic mode.The fluorescence emission is mainly polarized along the same direction as the incident polarization,showing a high degree of linear polarization.For y-polarized incidence,the fluorescence is enhanced by a factor of 8 resulting from the fact that magnetic mode is only excited under oblique incidence.The polarization of the fluorescence deviates from the incident polarization because of the combined contribution from both electric and magnetic modes.The fluorescence assisted by SRR-based metasurface can be controlled by changing the incident polarizations from different incident planes.In summary,this paper uses metallic micro-nanostructures to realize the excitation,characterization and manipulation of surface plasmon polaritons,including the propagating surface plasmon polaritons on the single-crystalline nanoplates and the local surface plasmon polaritons on the gold SRR-based metasurface,and the corresponding explored fluorescence enhancement and manipulation applications.These results imply potential applications in low-loss nanowaveguides,nanoscale light-matter control devices and expand the applications of metallic metasurfaces to the fields of fluorescence spectroscopy,nanosources,intergrated biosensors,and so on.