双层微金字塔结构耦合空间光调制的光子纳米射流研究  

Study on Photonic Nanojet of Bilayer Micropyramid Structure Coupled with Spatial Light Modulation

作　　者：孙泽华 刘卫国[1] 葛少博 刘丙才[1] 吴春芳 惠迎雪[1] SUN Zehua;LIU Weiguo;GE Shaobo;LIU Bingcai;WU Chunfang;XI Yingxue(Shaanxi Province Key Labotatory of Thin Films Technology and Optical Test,School of photoelectric Engineering,Xi'an Technological University,Xi'an 710021,China)

机构地区：[1]西安工业大学、光电工程学院、陕西省薄膜技术与光学检测重点实验室,西安710021

出　　处：《光子学报》2022年第12期231-239,共9页Acta Photonica Sinica

基　　金：科技部政府间国际科技创新合作重点专项(No.2018YFE0199200);陕西省科技厅项目(No.2022JM-345);应用物理化学重点实验室项目(No.61426020205);陕西省教育厅科研计划(No.21JY018);西安工业大学光电工程学院院长基金(No.2019GDYJY02)。

摘　　要：提出一种异质材料双层微金字塔结构耦合空间光调制的光子纳米射流光学元件,实现了光子纳米射流的动态可调。通过时域有限差分法进行仿真计算,分析了微结构与背景折射率对比度减小时,光子纳米射流性能特征变化的基本规律。研究结果表明,改变液晶分子的旋转角,焦距变化范围由6.1λ达到了22.3λ,衰减长度最长达到36.5λ,与双层微球结构耦合液晶光子纳米射流相比提高了10λ。随着微结构与背景介质折射率之比的减小,半高全宽增大,聚焦效率的调节范围可以达到16.9%~43.2%,此时,焦点逐渐远离微结构,能量向远场传输。借助于液晶这一空间光调制手段,双层微金字塔结构光子纳米射流实现了大范围的焦距调节和超长的传播长度,为光子纳米射流在光电探测、光学捕获等方面的应用提供理论支持。When a planar wave illuminates the microstructure of a dielectric material,it will appear in the shadow surface of the high-intensity energy gathering area and radiate to the far field,which is the photonic nanojet effect.Due to its strong focusing and ability to break through diffraction limits,the photonic nanojet has broad application prospects in the field of biological detection and optical characterization.Since the concept of photonic nanojet was proposed in 2004,researchers have explored the factors influencing the performance characteristics of photonic nanocrystals by changing various parameters.The results show that the formation of photonic nanocrystals is related to the microstructure shape,the incident wavelength and the ratio of the microstructure to the refractive index of the background.Although different photonic nanojets can be obtained in relevant studies,dynamic regulation can not be achieved.Liquid crystal has entered the field of scholars studying the phenomenon of photonic nanojet because of its tunable external field,providing more possibilities for subsequent studies.Subsequently,the method of combining with liquid crystal to change refractive index contrast and realize tunable photonic nanocrystals is proposed successively.However,most of the existing liquid crystal photonic nanojet is developed around the microsphere structure.When considering the microstructure of liquid crystal combined with the gradient profile of heterogeneous materials,the tunability of its light field deserves further study.This paper proposes a photonic nanojet optical element coupled with space light modulation of heterogeneous material bilayer micropyramid structure,which uses the liquid crystal as the background medium,and changes the rotation angle of the liquid crystal molecule by applying external forces to reduce the ratio of the microstructure to the refractive index of the background,and to realize the dynamic adjustment of the photonic nanojet.The Finite Difference Time Domain(FDTD)method is used for s

关 键 词：MIE散射理论 光子纳米射流 时域有限差分 空间光调制 微纳功能结构 

分 类 号：O436.2[机械工程—光学工程]