摘要
针对硫化锌表面微纳米结构在中远红外波段7~10μm的增透性能开展理论及实验研究。基于时域有限差分软件建立物理模型,理论研究微结构参数变化对减反性能产生的影响,依据红外光谱值分布图宏观展示微结构参数与透过率的关系。利用飞秒激光在空气环境中制备不同规格的微纳米结构阵列,通过实验实现了设计的结构。分别测试样品在中远红外波段7~10μm范围内透过率,其中8μm的网格结构在8.5~10μm波段的平均透过率可提高4%,在10μm波长处透过率提升7%。实验结果表明所制备的结构具有良好的抗反射性能。对比结果显示实验所示透过率变化趋势与仿真结果具有一致性。
Zinc sulfide is a widely used infrared window material.Due to its high refractive index and strong surface Fresnel reflection,improving its anti reflection performance in the infrared band is of great significance.The traditional method to improve the antireflective performance is to prepare a film on the surface of zinc sulfide,but the antireflective film has the disadvantage of detachment and it is a limited antireflection effect on infrared signals with a wide spectrum and a large angle incidence.Preparing subwavelength structures on the surface of zinc sulfide can effectively improve its antireflective performance.This can be achieved by adjusting the microstructure parameters.Femtosecond laser processing has unique advantages of programmability and non-contact,making it a promising one-step manufacturing method for subwavelength microstructures.In this paper,the finite difference time-domain method is used to simulate the antireflection characteristics of the zinc sulfide surface structure,which is prepared by femtosecond laser processing,and then the infrared transmittance of the structure array surface is measured.This article is based on zinc sulfide material,simulating and preparing one-dimensional strip structure and two-dimensional grid structure and further testing the infrared transmittance of both structures.Firstly,FDTD software was used to simulate and calculate the infrared transmittance characteristics of the zinc sulfide surface structure.Determine the unit structural parameters of the structural array by simulating the height of the strip structure.On this basis,two types of structural arrays with different spacing were designed,and the simulation results showed that as the spacing between structures decreased,the transmittance increased.The trend exhibited by one-dimensional strip structures and two-dimensional grid structures is consistent.Secondly,two types of structural arrays were prepared using femtosecond laser processing.The test results indicate that as the spacing between the one-dimensional strip structures decreases,the transmittance tends to increase,which is similar to the trend shown by simulation.The two-dimensional grid structure with small spacing has higher roughness,so the structure array with 8 spacing has better transmittance.In actual processing,it is necessary to comprehensively consider the influence of surface roughness and ablation degree on the transmittance,and reduce the Fresnel scattering of light waves by edge cracks.Finally,the transmittance of the samples was tested in the range of 7~10μm in the mid to far infrared bands.The structure array with a spacing of 5μm increases the infrared transmittance by approximately 6%at wavelengths 9.5~10μm.The grid structure with a spacing of 8μm can increase the average transmittance by 4%in the 8.5~10μm bands and nearly 7%at the 10μm wavelengths.In addition,the transmittance spectrum measured in the experiment has good transmittance in the long wavelength range,which is related to the scattering effect of nanoscale structures generated by laser processing at different wavelengths,the surface scattering effect of non-uniform micro nano composite structures is more pronounced at shorter wavelengths.Compared with the simulation result,it was found that the overall transmittance of zinc sulfide decreased.The overall decrease in the transmittance of zinc sulfide samples is related to two factors:the first reason is the light absorption effect caused by structural defects in femtosecond laser processing,part of the light is absorbed by zinc sulfide,and the second reason is the diffraction and light scattering effects caused by non-uniform surface particulate matter generated by laser processing,which deflects the incident light along the beam transmission path.The experimental results indicate that the prepared structure has good anti-reflection performance,indicating that the method used in this paper has a positive effect on improving the transmittance of zinc sulfide.This provides a reference for studying the transmittance of zinc sulfide in the mid-infrared band.
作者
罗兴
李明
毛建勇
LUO Xing;LI Ming;MAO Jianyong(State Key Laboratory of Transient Optics and Photonics,Xi'an Institute of Optics and Precision Mechanics,Chinese Academy of Sciences,Xi'an 710119,China;University of the Chinese Academy of Sciences,Beijing 100049,China;School of Electronic Science and Engineering,Xi'an Jiaotong University,Xi'an 710049,China)
出处
《光子学报》
EI
CAS
CSCD
北大核心
2023年第7期67-75,共9页
Acta Photonica Sinica
基金
国家自然科学基金(No.62275266)
国防科技基础加强计划技术领域基金项目(No.2020-JCJQ-JJ-514)
陕西省重点产业创新链(群)(No.2020ZDLGY01-06)。
关键词
飞秒激光
时域有限差分法
增透性
抗反射微结构
硫化锌
Femtosecond laser
Finite-difference time-domain
Antireflective property
Antireflective microstructure
Zinc sulfide
作者简介
第一作者:罗兴,luoxing_098@163.com;通讯作者:李明,liming@opt.ac.cn。
