Research On High Performance Surface Lattice Resonances And Sensor Based On Metal-Insulator-Mental Gratings

Micro-nano photonics has been widely used in various fields of electronic communication,chemical materials,and biomedicine.Research on small-size,long-life,and high-performance micro-nano optoelectronic devices has become a current academic hotspot.The emerging surface plasmonology in the interdisciplinary research fields of nanoscience,photonics and electronics has the characteristics of local field enhancement related to the excitation of light frequency,so as to promote the development of new principles,new structures and high-performance optical devices.However,traditional surface plasmons have a short propagation distance,small propagation volume,and high scattering loss(low Q value),these shortcomings have hindered its development and application in micro-nano photonic chips severely.In recent years,scientists have designed various micro-nano unit structures and arranged them periodically,so that the localized surface plasmon resonances(LSPRs)supported by metal nanoparticles and the Rayleigh anomalous(RAs)diffracted light supported by the spatial arrays interact with each other.The coupling produces Fano-shaped resonances,that are called surface lattice resonances(SLRs).SLRs have the advantages of low scattering loss,large-scale field enhancement,and energy propagating along the interface,that enhance the distance and area of the interaction between light and matter.In this paper,we use the excellent characteristics of SLRs to design one-dimensional gratings based on two different structures of metal-insulator-metal(MIM),propose high-Q SLRs with tunable wavelength,and study their sensing performance.1.We propose a kind of SLRs based on the vertical metal-insulator-metal(V-MIM)grating.The V-MIM is composed of gold(Au)and silicon dioxide(SiO₂)alternately superimposed,that embedded in homogeneous dielectric environment.Firstly,we obtain the parameters of the V-MIM grating that can achieve the maximum quality factor by scanning the width,height and period of the V-MIM grating sequentially.The SLRs can be excited in the V-MIM grating with a narrow linewidth of 0.8nm in the near-infrared band corresponding to a quality factor of Q=1232 for ?=0°,the quality factor can still achieve Q=159 when the incidence angle increases to 50°,which is three times higher than the quality factor of SLRs excited by traditional single layer grating.Additionally,we scan the azimuth parameters,so that the SLRs excited in V-MIM grating can be tuned in the wavelength range of nearly 1000 nm,that is more than two times longer than that of the traditional SLRs.The study of the near-field distribution of the V-MIM grating found that the high-Q SLRs originate from the quadrupolar resonance induced between two metals nanorods under normal incidence.We use the theoretical calculations of LSPRs and RAs to verify these simulations,and the results follow(-1,0)diffraction order.2.We propose a kind of SLRs based on the horizontal metal-insulator-metal(H-MIM)grating.The H-MIM grating excites SLRs with higher performance,that is illustrated by the comparative analysis with the V-MIM grating.There exist Fano-shaped narrow dips locating around 1240 nm within the flat transmittance spectra for ?=45°,the transmittance dip is centered at ?₀=1243.6 nm and has linewidth of 1.2 nm for the H-MIM grating.The corresponding quality factor reaches Q=1036,which is more than three times larger than the quality factor Q?328 of V-MIM grating.The research on the factors that influence the resonance spectrum of SLRs excited by the two structures,including the metal material,the incident angle and the gap width(the distance between the two metals).The results show that the quality factor of SLRs excited by H-MIM grating is much larger than that of V-MIM grating.We can observe from the near-field distribution of the two structures that the principle of the high-Q of the H-MIM grating is achieving out-of-plane quadrupolar SLRs,and the field intensity enhancement factors of H-MIM grating can reach 300.As a comparison,only dipolar SLRs can be excited in V-MIM grating under the same conditions.Quadrupolar can suppress radiation loss greatly,thereby H-MIM grating achieve high-Q.These results of the simulations follow(-3,0)diffraction order.3.We study the sensing performance based on H-MIM grating and V-MIM grating.When the refractive index of the substrate is 1.45 and the refractive index of the environmental increases from 1.40 to 1.50 in 0.01 steps,we study the SLRs of(-3,0)and(-4,0)diffraction order excited by the H-MIM and V-MIM grating.Corresponding refractive index sensing,thus obtaining dual resonant wavelength transmission valley refractive index sensing.We obtain the double resonance refractive index sensor by calculating the wavelength shift of the transmittance dip under different refractive indexes.The results show that the sensitivities of H-MIM are 373.6 nm/RIU and 259.1 nm/RIU,and the sensitivities of V-MIM are 334.0 nm/RIU and 191.6 nm/RIU.