Enhanced Terahertz Modulation And Control Devices Based On Metal Nanostructures And Their Application Research

Terahertz(THz)technology has broad application prospects and it is one of the current research hotspots.The applications of THz technology require the support of highperformance THz modulation and control devices.However,limited by the properties and structures of traditional materials,THz modulation and control devices based on traditional materials cannot meet the requirements of high-performance THz system applications.Therefore,new materials and methods are urgently needed to realize highperformance THz modulation and control devices.At present,the development of crossdisciplines has promoted the application of nanotechnology in the field of THz technology.Metal nanostructures with localized surface plason resonance characteristics provide a new research direction for the development of THz modulation and control devices.In this dissertation,the THz modulator and beam splitter based on metal nanostructures can significantly improve the modulation of THz wave and optimize the transmission path of THz-optical system,and provide new methodss and ideas for expanding the specific application of THz functional devices.The main research contents of this dissertation are as follows:1.A silicon(Si)-based THz modulator based on Ag nanoparticles is proposed.Ag nanoparticles with localized surface plason resonance property were used to enhance the light absorption of Si,and the modulation of THz wave in the frequency range of 0.325-0.5 THz was realized.The electric field distribution and absorption power density distribution at the cross section of Ag nanoparticles-Si structures were obtained by simulation.The simulation results further confirm that the localized surface plason resonance characteristic of Ag nanoparticles can cause strong local electric field enhancement at the surface of Si substrate,leading to its absorption enhancement.Therefore,the theoretical simulation and experimental results show that the modulation performance of Si-based THz modulator can be significantly improved by the Ag nanoparticles.2.A flexible multispectral beam splitter based on silver nanowire/graphene composite film is proposed.The beam splitter was prepared by spin-coating of the silver nanowire/graphene blend solution on polyethylene terephthalate(PET)substrate.The THz reflectivity is about 90% in the broad frequency range of 0.5-1.5THz,and the transmittance of visible light is more than 86%,which indicates that the beam splitter has an efficient multi-spectral beam splitting performance.The bending experiment proves that the beam splitter has high mechanical stability.A visible/infrared imaging system was built,and the beam splitter was used as a visible/infrared beam splitter.Clear optical and infrared imaging results are proved that the multispectral beam splitter can well realize a compact visible/infrared multispectral imaging system,which has a high practical value.