| There are many free electrons on the surface and inside of the metal.Plasmon is the free electron gas groups formed by these electrons.Surface plasmon refers to the free electron gas groups existing on the metal surface.Under certain circumstances,when light is irradiated to the metal,it will cause the free electron gas groups on the surface of the metal structure to oscillate,which forms the surface plasmon resonance(SPR).When the size of the metal particles is much smaller than the incident wavelength,the free electron gas groups will oscillate along the surrounding nanoparticles to form localized surface plasmons(LSP).Optical nanoantennas based on LSP have a wide range of applications in the fields of electric field localization,detection sensing,and nonlinear optics.In this paper,two optical nanoantennas are designed based on the physical principles and characteristics of surface plasmons.The finite element method is used to simulate and verify the characteristics of the nanoantenna.In-depth study of its inherent physical mechanism of generating electric field enhancement effects and its application in surface-enhanced Raman scattering.The main contents are as follows:(1)We briefly introduced the research history,basic theory,the concept and characteristics of surface plasmon.And we also introduced the free electron gas model of metal in detail and analyzed the transmission surface plasmon and local surface plasmon.(2)The principle,characteristics and application of optical nanoantennas based on the principle of surface plasmon were introduced.And the influence of geometric parameters on the resonance wavelength of nano-antennas was also analyzed.The electric field enhancement effect of bowtie nanoantenna was also introduced in detail.(3)The research history and working principle of Surface Enhanced Raman Scattering(SERS)were explained,the characteristics and preparation requirements of surface enhanced Raman scattering were analyzed.And the applications of surface enhanced Raman scattering were introduced.(4)A V-hole bowtie nanoantenna based on the surface plasmon was designed.The role of the V-shaped hole in the bowtie antenna structure was analyzed by the electric field enhancement diagram and the charge distribution diagram.The simulation results show that the designed antenna can localize the incident light within the nanometer scale and produce a strong electromagnetic field local effect.(5)Composite nanoantenna arrays were simulative designed for energy harvesting in visible range.Due to the interaction among rectangular nanoaperture,staircase bowtie and different layers of the staircase bowtie,the designed nanoantenna exhibits an ultrahigh localized intensity enhancement,and the composite nanoantenna can confine electric field distribution uniformly around the bowtie in direction.The excellent dual-resonance enhancement performance of the composite nanoantenna makes it especially suitable for surface enhanced Raman scattering(SERS). |
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