径向偏振光的产生与应用

摘要

相比于其他具有传统偏振模式的光束，径向偏振光拥有更为优秀的轴向中心对称性(这种特征在传输过程中保持不变)。人们投向径向偏振光的关注越来越多。径向偏振光在高数值孔径条件下的聚焦特性在纳微级制造、操控中得到很多且正变得越来越多的应用。在这篇论文中，我们首先试图理清径向偏振光的数学理论基础，仔细地阐述径向偏振光的光束特性和紧聚焦特性，并展示一些径向偏振光在紧聚焦条件下的示意图。接着，我们介绍了利用两束偏振正交的线性偏正高斯光束产生径向偏振光的方法；总结了理想的径向偏振光与通过二元衍射光学器件产生的径向偏振光间的吻合度，以及该吻合度与传输距离的关系。作为补充，其他一些产生径向偏振光的方式也被介绍出来。紧接着，一项基于径向偏振光紧聚焦特性，被运用于微粒子操纵的应用技术（我们称之为三维光学链操纵技术）被展示出来。为此，我们设计了一个光学衍射器件来调制径向偏振输入光的位相。在紧聚焦情况下，一个光学链能产生的原因是光束通过光学衍射器上两个同轴区域时产生的位相变化，这样的位相变化使得聚焦场附近的空间中产生明暗交替的光场。最后，我们论述了另外一些将径向偏振特性转化到实际运用中的方法。

关键字：径向偏振轴对称高数值孔径聚焦相干叠加三维光学链

Abstract

Compared with other uniformly polarized beams , the radially polarized beam performs perfect spatial axial symmetry and this special character kept when it transmits in free-space .This peculiarity gives rise to unique high-numberical-aperture focusing properties which has found important applications in nanoscale manufacture and manipulation . In this paper , we first overview those introductions we talked above .In the same time ,We also try to explain the mathematical concepts of radially polarized beam ; show some simple images of its focus properties .Then , we present a theoretical investigation of a technique for converting two orthogonally lineary polarized Gaussian beams into a radially polarized beam .We have shown the degree between the real radially polarized beam and the beam we created by a simple binary diffractive optical element ，further more，we show the results about how the transmission-distance influences the degree .By the way , we also talk about some other ways for generating radially polarized beam .After that , an application based on the focus property of radially polarized beam ,which we called optical chain ,used in particle-manipulation is shown . A diffractive optical element is designed to spatially modulate the phase of an incoming radially polarized Beam .For a tightly focused beam a three-dimensional optical chain can be formed because of the difference in the Gouy phase shift from two concentric regions of the diffractive optical element. At last , we present a lot about how those characters of radially polarized beam can be transformed into real applications.

Key Words : Radially polarized Axial symmetry High-NA focusing properties Coherent superposition Three-dimensional optical chain

目录

摘要............................................................................................................................ I Abstract ........................................................................................................................ I I

1 前言 (1)

2 径向偏振光的数学基础和特性研究 (2)

2.1 径向偏振光的数学基础 (2)

2.2 径向偏振光的紧聚焦特性 (3)

3 径向偏振光的产生 (7)

3.1 腔外相干叠加产生径向偏振光 (7)

3.2 利用圆形布鲁斯特棱镜产生的径向偏振光 (11)

3.3 利用亚波长光栅产生径向偏振光 (14)

4 径向偏振光的应用 (16)

4.1 紧聚焦径向偏振光产生三维光学链捕捉金属粒子 (16)

4.2 径向偏振光在激光切割中的应用 (20)

4.3 径向偏振光的其他应用 (24)

5 总结 (27)

致谢 (28)

参考文献 (29)