基于二元光学的可调控自弯曲艾里光束研究

Airy beams are potentially useful in applications of particulate control, laser weapons, and laser processing due to their unique properties of self-bending, nondiffraction and self-reconstruction. Generating an Airy beam need a grayscale phase element which present disadvantages of high cost, complicated processing, and low laser damage threshold, leading to limited applications of Airy beams. In this project, we propose a new method in which the grayscale optical phase elements are replaced by Binary Optical Elements (BOEs) to generate tunable Airy beams. Specifically, the quantization error caused by binarization process and the regulation of the bending direction and angle of Airy beams are analyzed first, then an evaluation function is set up to establish the theoretical foundation of generating accurate tunable Airy beams through BOEs. Based on the result of calculation, BOEs are designed and fabricated experimentally, then a femtosecond Airy light bullet testing system is set up for exploring applications of high-power and short-pulse Airy light bullets. Implement of this project will play a pushing role in exploring new physical principles and optical properties of Airy beams, which may find wide applications in civil and military industries.

艾里光束具有自弯曲、无衍射和自愈三大优良特性，在微粒操控、激光武器、激光加工等方面具有良好的应用前景。传统的艾里光束产生方法需要采用具有灰度位相分布的器件，其造价较高、生产困难、抗激光损伤阈值低，严重限制了艾里光束的实际应用范围。本项目系统研究基于二元光学元件生成可调控的艾里光束的方法，解决艾里光束应用的基础问题。具体研究思路为：分析二元化过程导致的量化误差的原因，摸索精确调控艾里光束的弯曲方向与角度的具体措施，并建立最优化评价函数，探索采用二元光学元件生成高质量可控艾里光束的理论基础。在此基础上，设计制备二元光学器件，并搭建飞秒艾里光子弹测试装置，对高功率短脉冲的艾里光子弹进行应用方面的探索。通过本项目的实施，能够探索发现艾里光束的新的物理原理和光学特性，为艾里光束在工业生产和军事武器等其它实际应用奠定基础。

研究过程基本按照原计划执行，一些研究内容稍作调整。理论方面，系统地研究了现有灰度位相器件生成艾里光束的理论，深入了解艾里光束传播特性。建立 BOE 生成孪生和圆环艾里光束的物理模型，分析倾斜因子对减少艾里失真的物理原理及最优化的取值方法。实验研究方面，结合激光直写设备和反应离子刻蚀机的加工特点，设计了可实际加工的最优化二元位相结构，采用激光直写设备制备石英二元位相掩模版，并研究最优化的激光功率、脉冲宽度、刻写速度等刻写参数。采用反应离子刻蚀机对已制备的掩模版进行加工，制作出二元微纳位相结构，对微纳结构进行表征，测量其表面形貌，并与理论设计相对比，优化直写和刻蚀制备过程工艺与参数。在应用研究方面，搭建了以氦氖激光器为光源的孪生艾里光束检测系统，测量光束的光强分布、自弯曲轨迹等物理量，并将其与理论设计相对比，并将其应用于显微成像光源，获得了大视场范围，高对比度的双层艾里光束照明系统。