Excitation And Application Of Fano Resonance On Surface Plasmon Supersurface

Surface plasmon?SP?is an electromagnetic wave coupled by external incident light waves and free electrons on a metal surface,which is generated on the surface of the metal and the medium and propagates forward.Due to the intense electromagnetic coupling effect of the artificially designed structure,it exhibits excellent optical properties such as induced transparency,Fano resonance,stealth characteristics,negative refractive index and transmission enhancement.However,the implementation of a single induced transparency and Fano resonance severely limits the development in the field of optics.In practical applications,it is eager to achieve high-quality multi-frequency domain plasma-induced transparency and resonance.In this paper,through the coupling and excitation of the modulated plasma mode,high-quality factor multi-frequency domain induced transparency and Fano resonance phenomenon are realized.The main work contents are as follows:First,we theoretically and numerically demonstrate multi-spectral plasmon induced transparency?PIT?in three-dimensional metamaterials.By moving the vertical middle nanorod to break the structural symmetry,the structure presents single-spectral or dual-spectral PIT windows,while it exhibits multi-spectral PIT windows at the laser wavelengths with He-Ne,ruby Cr³⁺and Kr,via moving the bottom nanorod.The quasi-static interaction model reveals that the near-field coupling strength between nanorods increases with the movement of the nanorod.This wor k provides a way to obtain multi-spectral PIT in an easily fabricable nanostructure.To improve the quality factor of the spectrum,we show multiple Fano resonances in an integrated single dark mode hybrid metamaterial waveguide structure.With a symmetrical pattern,the design shows double sharp Fano peaks.By breaking the structural symmetry,a quadrupole mode on middle vertical cut wire is excited and further results in multiple Fano resonances through both the diffracted waves and near-field coupling with bright-dark mode.Based on the above-mentioned properties,we show a high Q-factor refractive index sensor with figure of merit values of 330 and281.Interestingly,these Q-factors of Fano peaks can be increased to 1357 and 361 to improve the sensing performance,by capping a silicon layer on the metal surface.This letter provides a way to obtain multiple high Q-factor Fano resonances,which can widen channels for fabricating device in biochemical sensing.Last,we design and numerically analyze high-Q multiple Fano resonances based on a hybrid metamaterial waveguide?HMW?structure,which consists of T-shaped gold cut wires placed on dielectric board waveguide.Compared to the above two work,this is a high-Q multi-line Fano resonance realized by a hybrid metamaterial waveguide structure that does not break in symmetry.The physical origin of obvious Fano behaviors is explained by the three-level plasmonic system and slab waveguide theory.The largest Q-factor reaches 547,and modulation depth of the peak C can get nearly 100%,which can perfectly realize Fano switch function.Combining the cramped spectral lines with large near-field confinement,we demonstrate an optical refractive index sensor with a sensitivity of 4920 nm/RIU and a figure of merit o f 188.This work provides a way to obtain multiple high Q-factor Fano resonances,which can widen channels for fabricating device in biochemical sensing,optical switching.