The Study Of Perfect Absorption And Its Application Based On Plasmonic Coupled Structures

Metamaterials are arranged periodically or non-periodically by sub-wavelength unit cells,with supra-conventional physical properties not found in materials in nature,and its emergence has triggered a variety of interesting optical phenomena.By changing the three-dimensional(3D)metamaterial to a planar micro-/nano-structure design,the field of metamaterial research has been successfully expanded to the field of metasurface.This not only overcomes the limitations of metamaterials in the optical band,but also greatly promotes the research of many fields including light focusing,light absorption,light capture,spectroscopy and sensing,imaging,emission process,nonlinear enhancement,etc.The excitation of surface plasmon(SP)by metamaterials or metasurface can achieve a strong local field enhancement effect,and the excitation of different surface plasmon(SP)modes greatly enriches the application of metamaterials or metasurface structures.In recent years,in order to promote the development of photovoltaic cells,the light absorption effect of achieving specific needs has become a hot topic.This thesis is intended to achieve a perfect absorption effect of high Q value by designing metasurface devices,and the photoelectric voltage effect of this type of design is analyzed,which will promote the development of many applications including photovoltaic devices.The main contents of this thesis are arranged as follows:(1)The research background and significance of metamaterials,metasurfaces,surface plasmons,perfect absorption effects and photovoltaic effects are introduced,and the structural arrangements of this thesis are introduced.(2)To introduce the material models used in this thesis: Drude model and theoretical analysis model: Norton equivalent network model;The principle of Finite Difference Time Domain(FDTD)method;And the commercial simulation software used in research,including FDTD Solutions(Ansys / Lumerical)and CST MICROWAVE STUDIO,which are based on FDTD algorithms.(3)At optical frequencies,we design an anisotropic metasurface to realize high-Q perfect absorption in numerical calculation.By establishing the Norton equivalent network model,we first reveal that the basic mechanism responsible for this phenomenon may be attribute to the coupling excitation of the localized surface plasmon(LSP)mode and the surface plasmon polariton(SPP)mode.This absorber can realize bifunctional switching and is expected to realize the energy conversion of photon-SPP-photon.Meanwhile,we analyze the control of the structural design on high-Q perfect absorption.(4)Numerically,we conducted a comparative analysis of photovoltaic characteristics of the metasurface structure based on the metal metasurface-dielectric spacer-metal substrate(MIM)structure and the metal metasurface-metal film-dielectric substrate(MMI)structure.The calculation results show that the resonance wavelength will cause the occurrence of photovoltaic peaks.From the analysis,we concluded that the LSP mode and SPP mode excited in the multilayer triangular metasurface will play an important role in the enhancement or the modulation of the photo-induced voltage.(5)To summarize and look forward to the full research.