广义加速光束的理论和实验研究

项目名称： 广义加速光束的理论和实验研究

项目编号： No.11474352

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 数理科学和化学

项目作者： 严绍辉

作者单位： 中国科学院西安光学精密机械研究所

项目金额： 74万元

中文摘要： 诸如Airy光束在内的某些光束在传播过程中横模会发生横向平移，这类光束称之为加速光束。直观上，加速光束在沿着一条曲线(一般为抛物线)传播。数学上，这种平移等价于一个坐标平移的几何变换，而加速光束是平移变换下（振幅）不变的近轴波动方程的一个解。基于几何变换，本项目将从理论和实验上研究广义坐标变换下的加速光束。理论上,我们首先分析共形变换(平移-旋转变换)下，近轴波动方程允许的变换不变的解。这类光束不仅会经历通常加速光束的横向平移，还会经历旋转，这可以看作广义加速光束。其次，我们研究在给定加速行为下（特定的平移和旋转），近轴波动方程的解所对应的同胚变换。实验上，我们用空间光调制器产生广义加速光束并用镜面扫描法测量光束的聚焦光场。最后，我们研究广义加速光束聚焦场的光学捕获特性。通过对广义加速光束的研究，提高对特殊光场的认识，为探索微观领域提供一种新的光学操控方法。

中文关键词： 广义加速光束；共形变换；同胚变换；光学捕获

英文摘要： The transverse modes of some laser beams such as Airy beams experience a lateral shift during propagation.These beams are called accelerating beams.Intuitively, an accelerating beam is seen to travel along a curve, generally a parabola.Mathematically, this lateral shift is equivalent to a geometrical transform of coordiante translation and the accelerating beams are viewed as the solution of the paraxial wave equation (PWE), the magnitude of which is invariant under the transform. Based on geometrical transforms, this project investigates theoretically and experimentally accelerating beams under more general transforms. Theoretically, we first seek the invariant solution of PWE under a conformal transfrom-consisting of translaton and rotation.The beams of this type experience not only a common transverse shift but also a rotation. We call them general accelerating beams. Second, we seek some homeomorphisms which guarantee that the PWE has a solution having a given acceleraton,certain translation plus rotation. Experimentally, we investigate how to create such an general accelerating beam throuth a spatial light modulator (SLM) and use the mirror-scan method to measure the focused fields of the beam. Finally, we direct the generated general accelerating beam into a focusing system to observe the optical trapping on particles.By the study of general accelerating beams, it is hoped to better our understanding of special optical fields and provide a new method of optical trapping for exploring microcosm.

英文关键词： General accelerating beams;Conformal transforms;Homeomorphisms;Optical trapping