Research On Fluorescence Emission Characteristics Controlled By Micro-nano Antenna Structure

Fluorescence sensing technology has been applied in many fields such as life science,energy,food safety and so on.With the development of informatization and intelligence,human needs higher sensitivity of fluorescence sensing.However,due to factors such as existing theoretical knowledge and experimental preparation conditions,the quantum efficiency and fluorescence intensity of fluorescent substances are still very low,making it difficult to meet human’s rapid development needs for fluorescent sensing.In recent decades,with the development of micro-nano optoelectronic technology,more and more researchers use micro-nano optical structure to improve the luminescence characteristics of fluorescent substances,and have achieved certain results.However,the proposed micro-nano optical structure can only improve the single-wavelength or multi-band fluorescence emission characteristics at the same time,and cannot simultaneously achieve the enhancement of certain wavelength emission and the suppression effect of certain wavelength emission.Many optical characteristics of fluorescence can be used for fluorescence sensing.For example,polarization characteristics can be used in the field of polarization-related fluorescence sensing and imaging.In these fields,enhanced polarization fluorescence excitation and far-field directional emission can improve sensitivity of fluorescence sensing.Based on the above,this paper studies two kinds of specific optical properties that can improve the specific optical properties of fluorescence.First,we propose a V-shaped hybrid antenna structure.since the Vshaped metal groove and the lens form an optical cavity,scattering and interference of fluorescence emission is formed,and a specific optical coupling mode is formed,which respectively enhances and suppresses dual-wavelength emission in the second near-infrared region,and the average fluorescence ratio value is increased by 42.8 times;At the same time,the emitted light can be focused to improve the collection efficiency of the fluorescent signal,thereby improving the sensitivity of the second near-infrared region ratiometric fluorescence sensing,which is beneficial to detection of low-concentration analytes or single molecules.Then,we propose a triangular dimer nanoantenna structure,which can simultaneously enhance the fluorescence emission characteristics from the excitation and emission processes.Through the study of the dimer material,we found that the silicon dimer has obvious enhancement effect on fluorescence emission under z-polarization and realizes far-field directional emission,while the silver dimer has good effect on fluorescence enhancement under x-polarization.Then,we analyzed the effect of the combination of the dimer,the size of the triangle’s right-angle side,and the spacing of the dimer on the fluorescence emission,and finally determined the optimal structure parameters.Compared with the bare light source,the fluorescence emission of the silicon dimer is increased by 7 times,and the fluorescence emission of the silver dimer is increased by 10 times.Finally,we investigated the effect of the dimeric nano-antenna on the fluorescence excitation process.Using 405 nm plane wave excitation,we analyzed the excitation electric field and found that both silicon and silver dimers can achieve enhanced fluorescence excitation.