基于金属线波导的太赫兹调控结构的性质及功能研究

In THz band, due to high absorption of dielectric materials, finite conductivity of metal materials, and broad bandwidth of this frequency range, waveguides suffer from deficiencies such as high attenuation rate, high dispersion, etc., which hinders the progress of THz devices. Bare metal wire THz waveguides, which support a plasmonic mode on their surfaces in THz range, because of their very low losses, negligible dispersion propagation and structural simplicity, become one of the most important candidates for effective THz waveguiding; thus structures based on metal wire waveguides play a key role in THz manipulation, and have great potential in THz applications. However, limited by the difficulties in structure manufacturing and experimentations, researches on these structures are inadequate till now. This project will carry on theoretical and experimental studies on surface grooves, sub-wavelength tips, and Y-shaped structures based on metal wire waveguides. Specifically, the project will reveal the underlying physics of interactions between these structures and THz waves,analyze how structural parameters related to physical properties, and explore the characteristics of filtering, phase shifting, binding, focusing, and splitting manipulation. Systematically evaluating these manipulation functions, the project will lay a ground for their applications. Moreover, integrating the above-mentioned structures, the applicant will propose a broadband THz near-field probe, and carry on studies concentrating on its sub-wavelength imaging characters; by elucidating the near-field interaction pictures between THz field and samples, and taking advantage of these interactions, the project will explore the applications of this probe in broadband THz super-resolution imaging.

在太赫兹频段，由于介电体材料的高吸收、金属材料有限的电导，及太赫兹较宽的频谱，导致波导面临高损耗、高色散等问题，阻碍了太赫兹器件的发展。裸金属线太赫兹波导，支持一类表面等离激元模式传播，因结构简单、低损耗、低色散的特性，成为高效太赫兹波导的重要候选之一；故基于该波导的结构在太赫兹调控中扮演关键角色，具有巨大应用潜力；而限于结构制作及实验的困难性，对这些结构的研究仍有很多空白。本项目拟对基于金属线波导的表面槽、亚波长针尖、Y字形三种结构展开理论和实验研究，揭示它们与太赫兹波作用的物理机制，分析结构参数与物理性质的关系，探索利用这些结构对太赫兹波进行滤波、移相、束缚、聚焦、分束等调控的特性，为其实用化奠定基础。进一步的，本项目将集成以上结构构建宽谱太赫兹近场探针，研究其亚波长成像性质，阐明针尖附近太赫兹场与样品作用的图像，掌握这些作用的规律，探索这种探针在太赫兹宽谱超分辨成像中的应用。

裸金属线太赫兹波导，支持Sommerfeld表面等离激元模式传播，因结构简单、低损耗、低色散的特性，成为高效太赫兹波导的重要候选之一。本项目针对数种基于金属线波导的调控结构与太赫兹波的作用机制进行了研究和揭示，对其物理图像进行了阐释，分析了结构参数与太赫兹场分布之间的关系，为其实现近场聚焦、分束等调控功能奠定了基础；项目针对一种宽谱超分辨成像近场探针针尖进行了分析，获得了针尖附近太赫兹电磁场与样品间相互作用的图像，分析了电磁场的模式，通过探针得到的太赫兹信号，可以反映样品的形貌、反射谱等信息，构建了可用于宽谱太赫兹近场亚波长成像的系统，为其在太赫兹成像领域的应用奠定了基础；项目开发了紧凑、轻质量、高稳定度的光纤耦合太赫兹时域光谱仪(THz-TDS)，从色散补偿、非线性效应、偏振效应、天线参数等方面对基于1550 nm 波长的光纤飞秒激光器激发的太赫兹时域光谱系统进行理论及实验研究；同时，项目针对偶极子太赫兹光电导天线的检测带宽进行了理论及实验研究，为优化结构参数制作大宽带和高灵敏度的太赫兹天线提供支持。.项目共完成期刊及会议论文7篇，授权专利13项，受理专利19项，在投期刊论文3篇。