基于SSP的双侧开口型金属光栅实现太赫兹波的场增强与紧聚焦  

Two-sided open metal grating based on SSP can realize field enhancement and tightly focusing of terahertz wave

作　　者：姜光科 胡晓雪 赵洁惠 刘思亮 王晓雷[1] JIANG Guangke;HU Xiaoxue;ZHAO Jiehui;LIU Siliang;WANG Xiaolei(Tianjin Key Laboratory of Micro-scale Optical Information Science and Technology,Institute of Modem Optics,Nankai University,Tianjin 300350,China)

机构地区：[1]南开大学现代光学研究所天津市微尺度光学信息技术科学重点实验室,天津300350

出　　处：《光电子．激光》2021年第7期760-767,共8页Journal of Optoelectronics·Laser

基　　金：国家自然科学基金(61875093)资助项目。

摘　　要：基于金属光栅结构的SSP色散曲线,本文设计了一种一侧均匀另一侧非均匀且中间开口排布的铜带光栅结构,用于在太赫兹波段实现紧聚焦和场增强。研究表明,当0.57 THz入射的平面波经双侧开口型金属光栅后,可产生明显的局域电磁场增强与紧聚焦效应,其中增强因子Q=59.9,紧聚焦焦斑的半高全宽约为7.5μm(1/70λ)。此外,将单个双侧开口型金属光栅视为一个独立的单元,将其在一维横向和纵向进行排列或延伸,研究了这种结构对太赫兹波的光场调控特性。研究发现,0.57 THz入射的平面波经横向排列的单元结构后可以生成一维的焦斑阵列,其焦斑阵列所对应的半高全宽约为7.5μm。同时,0.57 THz入射的平面波经纵向延伸的结构后可产生纵向焦线,其焦线的长度为100μm,并且焦线的宽度约为7.5μm。这种周期性结构所产生的焦斑阵列和纵向焦线在提高太赫兹近场成像的速度方面具有明显的优势。Based on the SSP dispersion curve of metal grating structure,a copper strip grating structure with uniform on one side and non-uniform on the other side with an open in the middle is designed in this paper to achieve tight focus and field enhancement in the terahertz band.Studies show that when 0.57 THz incident plane wave pass through the two-sided open metal grating,obvious local electromagnetic field enhancement and tight focusing effect can be achieved,in which the enhancement factor Q=59.9 and the full width at half maximum of tightly focal spot is approximately 7.5μm(1/70λ).In addition,the single two-sided open metal grating was considered as a unit and arranged or extended in horizontal dimension and longitudinal dimension to generated multiple type of focusing filed.We found multiple focal spots in one-dimensional can be generated when the 0.57 THz incident plane wave pass through the horizontal alignment structure,and the full width at half maximum corresponding to the multiple focal spots is about 7.5μm.At the same time,the focal line can be generated when 0.57 THz incident plane wave pass through the longitudinal extending structure,in which the length of the focal line is approximately 100μm and width of the focal line is about 7.5μm.The multiple focal spots and longitudinal focus line generated by this periodic structure have obvious advantages in improving the speed of terahertz near-field imaging.

关 键 词：太赫兹波 人工表面等离激元(SSP) 色散曲线 场增强 紧聚焦 近场扫描成像 

分 类 号：O539[理学—等离子体物理]