Micro/Nano Optical Switch Based On The Dependence Of Surface Plasmon On Unit Structure Edge Sharp Features

Surface plasmon(SP)includes surface plasmon polaritons(SPPs)and localized surface Plasmon(LSP).SP has the characteristics of subwavelength-scale,field localization and local field enhancement,thus it has important applications in nano-photonic devices,optical imaging,photovoltaic cell and so on.The extensive researches on SP have merged into a new field,called Plasmonics.In recent years,the researches on Plasmonics mainly focus on two aspects: one is the theory research about the physical mechanisms and rules for SP in subwavelength metal structure;the other is the application research about the design and construction of novel plasmonic devices.This thesis utilizes the finite-difference time-domain(FDTD)method to explore the EOT characteristics of periodic circular-sharp hole arrays in metal films with different unit structures,which reveal the dependence of SP effects on unit structural edge sharp distributions.After that,a novel plasmonic switch is designed and verified,which expand the scope of application of subwavelength metal structure in the field of communications and information processing.The main works are listed as follows:(1)Firstly,the basic concepts of SP and enhanced optical transmission(EOT)phenomenon are expounded.Then,several typical plasmonic switches and the current status of this study are reviewed.Lastly,model of electromagnetic wave propagation in the metal and FDTD method aresystematically introduced.(2)The EOT phenomenon of periodic circular-sharp hole arrays in metal films with different unit structures are numerically simulated by 3D-FDTD method,so as to investigate the dependence of SP on unit structural edge sharp distributions.It is shown that the SP is influenced by unit structural edge sharp distributions via the LSP resonance in the edge sharp.The effects of the edge sharp distributions at different direction on the EOT characteristics are different.Keeping the number of edge sharps fixed,edge sharp distributions can influence the number of edge sharps which has LSP resonance,so as to affect the EOT characteristics of periodic circular-sharp hole arrays.(3)A novel plasmonic switch is proposed.Firstly,according to the dependence of SP on unit structural edge sharp distributions,a novel plasmonic switch based on periodic circular-four-sharp hole arrays is designed,and it is numerically verified by using 3D-FDTD method.Then,the effect of unit structure parameters on the EOT characteristics is systematically investigated,and the results shown that the performance of optical switch can be regulated by adjusting the unit structure parameters.This plasmonic switch has the advantages of small size,simple structure,convenient operation and no pump light interference.