VO_2薄膜受脉冲激光辐照实验及理论计算  

Experiments and Theoretical Calculations of VO_2 Thin Films Irradiated by Pulse Laser

作　　者：刘志伟 路远 冯云松 刘瑞煌 胡杰 LIU Zhi-wei;LU Yuan;FENG Yun-song;LIU Rui-huang;HU Jie(Electronic Countermeasures Institute of National University of Defense Technology, State Key Laboratory of Pulsed Power Laser Technology,Hefei 230037,China)

机构地区：[1]国防科技大学电子对抗学院脉冲功率激光技术国家重点实验室,合肥230037

出　　处：《光子学报》2018年第10期103-109,共7页Acta Photonica Sinica

基　　金：国家杰出青年科学基金(No.61405248);脉冲功率激光技术国家重点实验室主任基金(No.SKL2013ZR03)资助~~

摘　　要：为了探究在脉冲激光辐照VO_2薄膜过程中,影响薄膜相变响应时间的因素,基于COMSOL对辐照过程进行仿真计算.建立辐照VO_2薄膜的物理模型,并设置模型的边界条件,利用红外脉冲激光辐照三组通过分子束外延法制备的VO_2薄膜,间接得到了薄膜平均吸收率,并将吸收率实验数据带入计算模型中.在仿真计算中,考虑了激光的功率密度.薄膜基底厚度和薄膜初始温度等因素对仿真结果的影响.实验结果表明:增大激光功率密度和初始温度.减小基底厚度均可缩短薄膜辐照中心相变时间,并且相变时间和激光功率密度呈指数衰减趋势.5 000 W/mm^2的激光辐照基底厚度分别为0.15mm、0.3mm、0.5mm的三组VO_2薄膜,达到相变的时间分别为157ns、250ns、455ns,相变时间随薄膜初始温度升高线性减小.在入射激光功率不明确时,可以通过给VO_2薄膜施加一个接近相变点的偏置温度,适当控制薄膜基底厚度等来缩短相变时间,这对VO_2薄膜防护激光干扰中相变响应时间的相关研究具有一定的借鉴意义.In order to explore the factors that affect the phase transition response time of VO 2 thin films irradiated by pulse laser,we simulated the irradiation process based on COMSOL.The physical model of irradiation VO 2 thin films was established first,and the boundary conditions of the model were set,the infrared pulse laser irradiated three groups of VO 2 thin films prepared by molecular beam epitaxy,and the average absorptivity of the film was obtained indirectly,the absorptivity experimental data was brought into the calculation model.The influence of laser power density,substrate thickness and initial temperature of VO 2 thin films on the simulation results were considered in the simulation.Experimental results show that:increasing the laser power density and initial temperature,decreasing the base thickness can shorten the phase transition time of the film irradiation center.What′s more,the phase transition time and the laser power density show exponential decay trend.The 5 000 W/mm 2 laser irradiated three groups of VO 2 thin films,respectively,their base thickness are 0.15 mm,0.3 mm,0.5 mm,the time of phase change is 157 ns,250 ns and 455 ns respectively.The phase transition time decreases linearly with the initial temperature of the film.When the incident laser power level is not specified,we can apply a bias temperature which is close to the phase transition point on the VO 2 film,and control the film substrate thickness to shorten the phase transition time.This study has certain guiding significance for the study of phase change response time in the VO 2 thin films defensing laser jamming.

关 键 词：激光辐照 防护激光干扰 相变响应时间 COMSOL仿真 VO2薄膜 

分 类 号：O434.14[机械工程—光学工程]