为了制备高质量表面周期结构，利用法布里-珀罗腔对飞秒激光进行时域整形，输出子脉冲间隔在1~300 ps内灵活可调的飞秒激光脉冲串，在硅表面诱导亚波长周期条纹。实验结果显示，利用飞秒激光脉冲串诱导得到的亚波长周期条纹明显优于原始高斯光诱导的亚波长周期条纹。利用子脉冲间隔为100 ps的脉冲串诱导的亚波长条纹最佳，条纹周期为1 008 nm，结构取向角为2.8°，边缘粗糙度为3.9 nm，可达到光刻工艺的标准。

Overview: With the development of modern manufacturing, the size of optical devices is gradually developing towards miniaturization, and integrated optics is also developing to become a topical area of research for many scholars. One of the methods used for producing micro/nano optical devices is femtosecond laser direct writing, a fine three-dimensional processing technique that has been extensively studied by many scholars for its applicability to most materials and can be applied to the fabrication of a wide range of optical devices. Micro/nano-optical devices prepared by femtosecond laser direct writing in crystals have been applied in a broad range of applications in different wavelengths. PMN-PT crystal with relaxed ferroelectric has attracted much attention in recent years for its superior piezoelectric property and large electromechanical coupling coefficient, and its application in the infrared band is more prominent, so the fabrication of the optical devices based on PMN-PT crystal has gradually become a relevant research hotspot. The LIPSS is one of the micro/nano-structures that can be processed by femtosecond laser direct writing. The LIPSS is prevalent in many materials and has been found in metals, semiconductors, dielectrics, etc. Similarly, LIPSS can be induced by femtosecond lasers in PMN-PT crystal. The LIPSS has a wide range of applications in the fields of anti-reflectivity, permanent coloration, and wettability. Nevertheless, the physical processes and the mechanisms involved in the formation of LIPSS have different interpretations in different materials. In this paper, we describe the LIPSS induced by femtosecond laser on the surface of the PMN-PT crystal and characterize it theoretically. We have achieved a change in the period of the LIPSS from 750 nm to 3000 nm after experimenting with different laser parameters. Afterward, we simultaneously obtained the phase transition of the LIPSS in PMN-PT crystal through temperature modulation, and this phase transition can be analyzed by the variation of the Raman spectra. At the same time, we have obtained the Curie temperature for the LIPSS structure that is approximately 10 ℃ lower than that of the PMN-PT crystal and have analyzed the phase transition process through the structural properties of the PMN-PT crystal. The results of our experiments and analyzes on the LIPSS in PMN-PT crystal reported in this paper can provide some experience for the subsequent development of the optical devices related to the LIPSS in PMN-PT crystal.

为进一步拓展微纳米周期超结构功能特性，满足光学周期超结构高精度设计需求，基于时域多分辨分析方法，从Maxwell方程出发，推导出微纳米三维半球光学周期结构表面散射耦合场，计算结果与时域有限差分方法结果吻合良好。给出微纳米三维半球光学周期结构表面场分布并数值计算微纳米三维半球光学周期结构表面微分散射截面，提炼分析填充材质、半球尺寸、半球间距等参量对光学周期结构表面散射场影响规律。结果表明：P偏振下电场分布更能突出周期结构表面结构单元轮廓；散射场值随入射角变大，在对应镜面散射角方向逐渐减小；在半径和波长值相当时，填充单元散射场峰值个数与探测范围内填充单元个数吻合；随填充半球间距增大，散射场的极大值数递增，且极大值对应的角度区间依次减小。

金属或半导体与介质分界面上的电子与光子互作用形成的光学表面等离激元（SPP）以及人工超构材料或二维原子晶体材料表面上的电子与太赫兹波或微波互作用形成的人工表面等离激元（SSP）是小型化与集成化太赫兹有源/无源器件和太赫兹超分辨率成像的重要物理基础。随着太赫兹科学技术的发展，太赫兹表面等离激元研究在国际上受到很大关注。本文介绍了传统的光学表面等离激元及其发展，详细阐述了太赫兹波段的人工表面等离激元（SSP）和石墨烯表面等离激元（GSP）的基本原理和发展历程，对表面等离激元在太赫兹波段的新型辐射源、无源器件、超分辨率成像及其他领域的应用进行了较为全面的总结和评述，并对该领域未来进一步发展的方向进行了展望。