Research Of Extraordinary Optical Transmission In Metal Micro-Nano Structure Based On Dispersive Medium FDTD Method

When electromagnetic waves are incident on the metal surface,the electrons on the metal surface and the photons in the incident electromagnetic wave are coupled to each other,causing the electrons on the metal surface to collectively oscillate,and the distribution state is also periodically changed.This periodic electronic oscillation mode is called It is a surface plasmons(SPs).According to their form of expression,they are generally divided into two categories: one is that it can propagate along the metal surface,the direction of propagation is parallel to the metal surface,and the direction perpendicular to the metal surface is exponentially decaying.We call it the surface plasmon.Surface plasmon polaritons(SPPs);the other is non-transverse mode,metal surface electrons can only be confined to special positions on the metal surface,such as near the nanoparticles,do reciprocating oscillation,we call it local Localized surface plasmon resonances(LSPRs),or localized surface plasmons(LSPs).The research of SPs-based nanophotonic devices is one of the hotspots in the world.SPs has unique physical properties and its application prospects are very promising.Such as biosensing,ultra-high resolution imaging,optical stealth and so on.Especially,SPPs play an important role in making the sub-wavelength hole array metal film structure break through the diffraction limit in the traditional sense,leading to the electromagnetic wave diffraction phenomenon that cannot be explained by the traditional electromagnetic wave diffraction theory.It plays a major role in creating a phenomenon that different from the traditional electromagnetic wave diffraction theory—Extraordinary Optical Transmission(EOT).It is precisely because of the discovery of the phenomenon of abnormal light transmission that the integration of photonic devices and electronic devices on one chip or even all-optical integration has the possibility that a new technological revolution is also impossible.Based on the finite-difference time-domain method of dispersive medium,this paper introduces the phenomenon of optical anomalous transmission as the core,introduces the basic physical properties of SPs,and deeply explores its excitation characteristics and coupling effects,and further explores the surface plasmon-based.The application prospect of theoretical light anomalous transmission phenomenon.The main work of this paper can be summarized as follows:1.Research on optical anomalous transmission phenomenon of window-type array metal film structure.Based on the conclusions of previous studies,a new window array structure is designed.The geometric parameters of the window structure include array.The transmission characteristics were investigated in detail,and the coupling effect between surface plasmons was observed by observing the electric field distribution,and the effect of the resonance effect of the Fabry-Perot-like cavity on the light transmission characteristics was investigated.2.The study of optical anomalous projection transmission of a mirror-symmetrical rectangular cavity metal grating structure is studied.This part mainly studies the abnormal transmission characteristics of the structure of a mirror-symmetrical rectangular resonator.The resonance effect characteristics of different cavity depth widths on incident electromagnetic waves are summarized,and the transmission spectrum can be linearly adjusted by adjusting its parameters.The results show that the depth of the embedded mirror rectangular cavity can be linearly adjusted for the transmission spectrum.3.An all-optical diode device based on surface plasmon is designed by using the characteristics of light anomalous transmission.Etching a nano-circular hole in the metal silver film,and adjusting the excitation of the surface plasmon by etching the annular groove around the hole,and the cavity resonance condition,by adjusting the composite evanescent wave to affect the incident electromagnetic wave the transmission characteristics are such as to positively promote light transmission and reversely suppress the effect of light transmission.Through many electromagnetic simulations,the influence characteristics of the annular groove on the transmission line are summarized,to get maximize the ratio of the positive and negative transmittance of the light,which provides a reference for the research of all-optical devices.