Investigation Of Plasmon Resonance Properties Of Vanadium Dioxide And Its Gold Nanoparticles Composite Structure

The localized surface plasmon resonance?LSPR?characteristic of precious metal nanoparticles is a kind of photon absorption phenomenon which is caused by the same incident electromagnetic wave frequency and the free electron oscillation frequency of the precious metal nanoparticles.It is very sensitive to the surrounding dielectric environment.Add another kind of dielectrically variable material around the precious metal nanoparticles is an important method to enhance the resonance tuning performance.Vanadium dioxide?VO₂?has a unique semiconductor metal transition?SMT?characteristic under thermal excitation.The optical,electrical and magnetic properties of VO₂ will change significantly during phase transition.At the same time,the dielectric constant of VO₂ will also change with SMT.This transition characteristic is reversible.Therefore,dynamic modulation of LSPR characteristics can be achieved by the combination of VO₂ and precious metal nanoparticles.VO₂ and its precious metal nanoparticle composite structure have potential application value in the fields of smart windows and tunable electromagnetic wave absorbers,but there are still problems of insufficient tuning ability.In view of the above,this paper has carried out the following two parts of research.Firstly,in order to enhance the tuning ability of VO₂ to the near-infrared transmittance and obtain the regulation mechanism,the discrete VO₂ particle structure was prepared by etching the continuous VO₂ film with dilute sulfuric acid?H₂SO₄?.The resonance characteristics of VO₂ nanoparticles and the influence of the coupling effect of different particle distance on the resonance properties of VO₂ nanoparticles were studied.The results show that the discrete VO₂ nanoparticles with resonance characteristics have a larger transmittance tuning amount in the near-infrared region than the continuous planar VO₂ film.It is increased by 156.7%at 1521nm.In addition,when the distance of the VO₂ particles is decreased,the coupling effect will become stronger,and the LSPR peak will have a red-shifted.At this moment,the tuning ability of the transmittance is also enhanced.Secondly,in order to improve the tuning ability of VO₂ to the LSPR characteristics of gold?Au?and obtain the regulation mechanism,a totally encapsulated three-layer VO₂ film/Au triangle nanoparticles/VO₂ film composite structure was proposed and fabricated.The differences in resonance characteristics among the three-layer composite structure,double-layer VO₂ film/Au triangle nanoparticles structure and double-layer Au triangle nanoparticles/VO₂ film structure were studied.At the same time,the effect of VO₂ film's thickness on the resonance characteristics of VO₂/Au/VO₂composite structure was also studied.The results show that the tuning range of LSPR peak will increase with the increase of VO₂'s cover rate of the resonance field of Au triangle nanoparticles array.Moreover,when the thickness of VO₂ is increased,the tuning ability of VO₂ to the LSPR of Au is further enhanced.In the experiment,the maximum tuning range is 112nm.On the basis of experiments,Finite-Difference Time-Domain?FDTD?method was used to simulate the optical properties of VO2 and its Au nanoparticles composite structure.The simulation results and experimental results were similar,and the above conclusions will contribute to the research of tunable optical devices.