Research On Enhanced Spectral Of Plasmon Nanostructures

The profound understanding and manipulation of the interaction between light and matter is the research goal that physicists dream about,and has long occupied an important position in the research field at home and abroad.When an electromagnetic wave interacts with a metal nanostructure having a sub-wavelength feature size,a phenomenon of collective oscillation occurs due to the interaction of the photons of the incident light with the free electrons on the surface of the metal structure,and a surface plasmon is formed on the metal surface.The Fano resonance with special asymmetric spectral lines originates from the near-field coupling of bright and dark plasmon modes.The bright state is a wide-band super-radiation mode that can be directly excited after the incident light acts on the plasma nanostructure,and the dark state is a narrow-band dark radiation mode that cannot be excited by the incident light.To date,Fano resonance has attracted the attention of researchers due to its special resonance linetype,strong local fields,high sensitivity,high quality factors,and various coupling methods.It has a promising application prospect in biochemical sensing,photonic devices,plasma switches,nano lasers and other fields.In recent years,with the rapid development of nano-preparation technology,various methods have been provided for the realization of Fano resonant metal nanostructures.This paper starts with plasmon resonance and analyzes the generation of Fano resonance and its application.Due to the strong local field properties of the Fano resonance,a crisscross-dimer metal nanostructure was proposed and studied under periodic array structure and scattering system.The main research contents of this paper include:1.Research on performance of SECARS based on multi-resonance system nanostructures.We theoretically studied the crisscross dimer periodic array structure can be applied to multi-resonant plasmon substrates,and proposed a new way for the generation and coupling of plasmon modes.The influence of the structural parameters on the resonance mode in the metal periodic array structure was studied in detail.It was proved that the coupling of three different modes of plasmon resonance can achieve a huge electric field enhancement effect,and can be applied to the enhancement of CARS signals in the visible and near infrared spectral range up to10¹⁵¹0¹⁶.The main factors for achieving the maximum SECARS signal include three:?1?The crisscross dimer periodic array structure satisfies excitation of multiple resonant plasmons at different frequencies;?2?Plasmon resonance can achieve spectral overlap with the input and output beams;?3?Different plasmon resonances have the same hot spots.2.Study on the performance of SECARS properties of nano structure based on Fano resonance.The Fano resonance phenomenon was achieved through the interaction between dipole resonance and magnetic dipole resonance.The dependence of the resonance position and the resonance mode on the geometric structure was analyzed.At the same time,the equivalent model of LC circuit is proposed to verify the magnetic dipole resonance mode.Based on the adjustment of structural parameters,a multi-resonant plasma mode in asymmetrical crisscross dimer structure was realized and it was verified that it could also be applied to CARS signal enhancement.