Study On Photothermal Effect Of Vanadium Dioxide Nanostructures

Micro-nano particles can convert electromagnetic irradiation into Joule heat under visiblelight,infrared and terahertz irradiation.Thus,the temperature of the particles is increased until the thermal equilibrium is reached.By adjusting the morphology,size,nanostructure and composition of the nanoparticles,the photothermal effect of the particles under the irradiation of incident light can be effectively adjusted.However,in some cases where the incident light intensity is strong or the light intensity cannot be accurately controlled,the material needs to be able to maintain a stable temperature under the condition of the irradiated light intensity changing,which requires the material's light absorption to be able to change the incident light intensity nonlinearly.In this paper,Vanadium dioxide(VO₂)can change drastically near the phase transition temperature,so that the temperature of the particles can be adjusted adaptively,and the temperature of the particles can be maintained near the phase transition temperature.The photothermal properties of Vanadium dioxide-Titanium nitride(Ti N)core-shell nanostructures in visible light range and single VO₂spherical particle as well as Au/VO₂ core-shell nanoparticles in terahertz range are calculated and preliminarily studied by using Volume Integral Equation Method(VIE)and Mie's theory.The details are illustrated as follows:1.We introduced photothermal effect mechanism and research progress of micro/nano particles;and introduced the basic theory of plasmon,including surface plasmon and localized surface plasmon.We introduced the numerical calculation methods of the Volume Integral Equation method and Mie's theory.2.We write the program code of VIE method,and compared the results of VIE method with that of Lumerical FDTD Solutions,and calculated the influence of mesh accuracy on the calculation results.In the visible range,the photothermal effect of VO₂-Ti N core-shell structure is calculated by VIE method and heat conduction equation.We studied the change of particle photothermal effect with particle shape,size and incident light intensity.3.For terahertz range,the optical absorption and thermal response of VO₂ spherical particles and Au/VO₂ core-shell particles are analyzed by using Mie's theory and heat conduction equation.We investigated the photothermal effect of particle size,phase transition temperature width,incident light intensity,thermal convection coefficient between particles and surrounding media.