A Study On The Characteristics Of Vanadium Dioxide For Laser Blinding Protection

With the rapid development of laser blinding weapons,the technique of laser blinding protection has attracted a surge of interest in the research community.As is one of the materials for protection,Vanadium dioxide（VO₂）has a reversible metal-insulator phase transition under external excitations.During the phase transition,there are remarkable changes in the optical,electrical,and magnetic properties of VO₂,which makes it become an ideal material for applications in various fields.Particularly,VO₂ is of great importance to the laser blinding protection due to its property of sudden change in infrared transmittance.This thesis focuses on the preparation of high-performance VO₂ film and the application of VO₂ for laser blinding protection.The main technical contributions are summarized as follows:1.After establishing the VO₂ crystal structure model,the electronic structures of VO₂prior to and after the phase transition as well as VO₂with oxygen vacancies are calculated via leveraging the First Principles.VO₂ is further theoretically analyzed in the application of laser blinding protection according to its phase change characteristics.2.The Drude-Lorentz model is exploited to research the optical constants of VO₂.Moreover,the characteristics of a single-layer VO₂ film is measured with an ellipsometer,after which the low-temperature complex refractive index of the actual prepared film is computed,leading to a theoretical basis for subsequent simulations.3.The TFCalc software is utilized to design and simulate a broadband multi-layer antireflection coating in the 3～5μm band,which tackles the issue of low transmittance of signal light in the 3～5μm mid-infrared window and guides the subsequent preparations.In addition,the FDTD Solutions software is used to design two focusing metasurfaces for laser protection systems based on VO₂ film and VO₂ cylinders,respectively,which solves the problem of low space utilization of VO₂ film and microlenes,providing a new way to design laser protection systems.4.VO₂ thin films are prepared by ion beam sputtering and post-annealing.The influence of substrate temperature and oxygen flow on the performance of VO₂ film is analyzed,when ion beam sputtering is used to prepare the VO₂film.Furthermore,the optimal annealing temperature of VO₂ film of different thickness is figured out and the electron beam evaporation method is applied to prepare the multi-layer antireflection coatings.5.A variety of lasers and a fourier infrared spectrometer are adopted to evaluate the characteristics and protective effects of the prepared single-layer VO₂ film and the multi-layer antireflection coating,which verifies the promising performance of VO₂ for laser blinding protection.