Vanadium Dioxide For Laser Protection

The rapid developing laser weapons are playing important role in modern wars.As one of the tactical weapon,laser blind jamming can not only disturb the regular function of the photoelectric devices but also blind soldiers temporarily,that cause the attention of the military,so the research on laser protective materials is becoming more and more important.As a typical phase transition material,vanadium dioxide?VO₂?demonstrates sharp metal to insulator transition?MIT?at 68 degrees,accompanying with abrupt changes in the optical and electrical properties.The infrared transmittance would be transformed from a high transmittance at low temperature state to high reflectance at high temperature state,with low phase transition threshold and high damage threshold,VO₂ meets the basic requirement of laser protection and is considered as a new intelligent material for laser protection.This thesis studies the laser protection of VO₂ in infrared band and the enhancement of its visible light transmittance.The main contents of this thesis are as follows.1.The phase transition mechanism and laser protection theory have been briefly analyzed.By introducing Drude model and Lorentz model,we studied the optical constant of VO₂.Based on effective medium theory,we analyzed the optical properties of vanadium dioxide nanogrid films,that provided the theoretical basic for the subsequent simulations and experiments.2.The TFCalc coating design software and optical devices simulation software FDTD Solutions were used to simulate the continuous film and nanogrid film,providing a directional guidance for the experiments.3.The parameters of reactive ion beam sputtering to fabricate VO₂ film were optimized and high quality films were obtained.Also the influence of post-annealing process on the quality of the film was studied,and the optimal annealing temperature was obtained.4.VO₂ microgrid films were prepared by semiconductor technology such as UV lithography and ICP etching,the parameters of the process were explored.5.The phase transition threshold and laser damage threshold of the film were tested with different kind of lasers.6.With the silicon photocell as the target,the laser protection experiment of VO₂ films were carried out.