Nonlinear Optical Properties Of Metallic Nanoparticles And Their Applications In Plasmonic Biosensors

The study found that metal nanoparticles and its polymer have abnormal lighttransmission performance, and its transmission spectra is influenced by the structure shape,symmetry, materials and incident light polarization. Through the combination of the metalnanoparticles with different shapes and sizes tuning the surface plasmon resonant mode ofthe metal nanostructures from, new nonlinear optical effect will be produced, such as Fanoresonance, electromagnetically induced transparency, Rabbi split, etc. and since Fanoresonance has the characteristic of narrow full-width half-maximum, high intensity ofresonance and sensitivity to the dielectric constant of the surroundings, it has very goodapplication prospect in the field of achieving of biological molecules sensor with highsensitivity. The current research on the Fano resonance mainly focuses on the research ofsingle Fano resonance characteristics. Based on the nanometer metal ring and the metalnano rods polymer and double-intersected split ring resonators, this article constructs themetal nanostructures with multiple resonant characteristics and explores its application inbiological sensing field.First, based on the3D FDTD algorithm simulation, we do the research on the Fanoresonance effect of the combination of the nano ring and nano rods. By tuning thestructure parameters, Multiple Fano resonance characteristics are produced. And by usingthe method of multilayer surface plasmon hybrid model and analyzing the characteristicsof electromagnetic field and the charge density distribution inside the nano structures, wedetermine the surface plasmon coupling hybrid model between different components(nanoparticles) inside the nano structure. In this way, the physical mechanism of multipleFano resonance effect is illuminated.Secondly, we designed and manufacture the double-intersected split ring resonatorsmetal nanostructures with Fano resonant nonlinear optical effect. By analyzing their nearfield charge distribution characteristics, we studied the relationship between the patterns ofsingle split ring resonators and optical characteristic of double-intersected split ringresonators and illuminate mechanism of production of Fano resonance. Then by using electron beam lithography (EBL), we made them and test the spectral signature of thestructure. And the degree of compliance between the simulation spectrum characteristicsand spectrum characteristics are good. Finally, through spin different molecules on thesurface of double-intersected split ring resonators, we analyze the biological sensingproperties basing on the Fano resonance. And Results show that the sensitivity ofbiosensor achieves470nm/RIU.In conclusion, by analyzing the characteristics of near field electromagnetic field andthe charge distribution inside the combination of metal nanoparticles structure, we definemechanism of production of the nonlinear optical effect (fee resonance). Also weconstructed and realized the two sets of metal nanostructures with multiple Fanoresonance effect more noble, and explored their application in biological sensing field.