Study On The Property Of Focusing And Absorption Of Plasmonic Nanostrucutres

Surface plasmons are waves that occur under the interaction between the freeelectron in the surface of metal and the incident wave. Although there has been ahistory of nearly100years on the research on the surface plasmons, surfaceplasmons do not show its extraordinary property at early time because of therestriction of technological development at that time. Nowadays, thanks to thebooming speed development of science and technology, especially the field ofmicro-electronics is developing and perfecting, it makes possible to fabricate ofmicrometer and nanometer scale electronic components and circuit, and so surfaceplasmons gain new attention by researchers.Surface plasmons own the characteristic of near-filed enhancement, so on basisof such property, recently much work has been done to miniaturize traditional laser,sensor, and solar cells to make the new generation under the nanoscale. In this paper,based on the FDTD Solutions commercial software, we design some plasmonicnanostructures to study the property of absorption and focusing.When studying the focusing property of plasmonic structures, we design anelliptical grating plasmonic nanolens with five etched concentric elliptical ring aswell as an elliptical hole in the center on a silver film. When the ratio between the xaxis and y axis of the elliptical ring as well as elliptical hole varying from1to0.1,we found that the ratio is linearly proportional to FWHM which exists in Z=20nmfrom exit plane of the nanolenses in x and y directions respectively. Meanwhile,there also exists a linear relationship between the ratio of the structure and the ratioof FWHM between x-and y-directions. During the process of varying its ratio, thefocusing size turns from96n m126nmto15nm52nm. On the other hand, the previous linear relationship does not exist when the ratio changing from1to2.When studying the absorptive property of plasmonic structures, we designplasmonic metamaterial nanopillar and nanoring absorbers and analyses theirabsorptive property in the visible waveband. Firstly, we present the detailedstructures of our two metamaterial absorbers and discuss different parameters on theabsorptive effect. Then we analyze the absorptive effect of these two absorbers underthe condition of larger waveband, different polarization states, and different incidentangles. Finally, the absorptive mechanism of these two absorbers has been discussed.Through analyzing the electric field distribution|Ex|and magnetic field distribution|Hy|as well as its energy flow distribution, we get the absorptive mechanism ofmetamaterial nanopillar absorber is the synergistic effect of the localized surfaceresonance enhancement and slow light mode and for the metamaterial nanoringabsorber the mechanism is the synergistic effect of localized surface plasmonresonance and Fabry-Perot (FP) resonance.