基于计算全息法，通过计算和模拟得到了涡旋光束与平面光束干涉所产生的位错条纹，用胶片记录位错条纹并制作成位错光栅，在自行设计搭建的光路中进行实验获得1~4阶的涡旋光束。实验结果表明，各阶涡旋光束的空心半径随着阶数的增大而逐渐增大，与理论分析相符合；实验进一步观察到各阶光栅的二级甚至三级衍射光束，当入射光束中心与光栅位错中心重合时，能够产生光强分布对称的涡旋光束，当光束中心和光栅中心不重合时，产生的涡旋光束的光强分布不对称。这为后续以涡旋光束为捕获光束的光镊实验的进一步拓展及应用提供了理论和技术支持。

Based on the computer generated holography, the dislocation fringes caused by the interference between the vortex beam and the plane beam were obtained through simulation and expriment. The dislocation gratings were made by films which recorde these interference fringes. With our own designed optical path, 1- 4 order vortex beam were obtained in the experiment. The experimental results show that radius of the vortex beam will increase gradually with the increasing the orders, which are consistent with the theoretical analysis. The second and third diffraction beams of the gratings are observed further in the experiment. The vortex beam of symmetrical intensity distribution can be produced when the center of incent beam overlaps with the cetnter of dislocation grating, otherwise, the distribution of the vortex beam will be asymmetrical if the center of incent beam does not overlap with the center of dislocation grating. This work provides theoterical and technical support for

根据光束扩展理论,以部分相干的电磁高斯-谢尔光束为研究对象,分析了电磁光束传输时其偏振特性的变化机理.结果表明,光源参数和大气湍流对电磁光束分量扩展的影响是导致传输过程中电磁光束偏振特性变化的原因.在真空中传输时,电磁光束两分量的相干性存在差异,导致传输时电磁光束两分量扩展快慢不同,从而引起传输路径上光束谱偏振度的变化.在大气湍流中,电磁光束两分量扩展的快慢与光源参数和大气湍流强度均有关,当传输路径较短时,电磁光束偏振变化主要与光源参数有关,变化特性与在真空中传输时的情况类似,而传输距离较远时,电磁光束偏振变化受大气湍流的影响明显,变化特性与在真空中传输时的情形存在不同.

According to the theory of beam spreading and taking electromagnetic Gaussian Shell-model beam as an object of research, the change in its spectral degree of polarization is studied by numerical analysis. Based on the numerical results, the mechanism that governs the change in polarization of an electromagnetic beam on propagation is discussed. The results show that the beam spreading of two components of an electromagnetic beam results in the change in polarization of beam directly, and the beam spreading is determined by source parameters and atmospheric turbulence. The difference between beam spreading of two components induced by coherence leads to the change in polarization in free space. The change in degree of polarization is influenced by source parameters and turbulence on propagation in atmosphere. The result is similar to that in free space over relatively short distance, which is mainly governed by source parameters. With the enhancement of turbulence over a su?ciently long

空间相位调制一直是设计新型自加速光束的重要方法.参照类贝塞尔光束产生的思路,从理论上提出了一种新型的自加速无衍射类贝塞尔-厄米-高斯光束,并从数值模拟和实验两个方面研究此光束沿不同轨道的演化.理论上通过对厄米-高斯光束进行相位调制,产生了不同模式的自加速类贝塞尔-厄米-高斯光束.采用分步傅里叶算法模拟了(0,1),(1,0),(1,1)和(1,2)阶类贝塞尔-厄米-高斯光束沿预设轨道的传输过程.采用计算全息和空间光调制技术在实验中观察了类贝塞尔-厄米-高斯光束沿预设轨道的传输,例如抛物、双曲、双曲正割和三维轨道.实验观察与理论结果符合得很好.实验验证了不同阶类贝塞尔-厄米-高斯光束的奇特光斑结构,验证了光束的非衍射特性及传输轨道的可控性,且理论模拟验证了光束的自修复特性.作为此前研究的类贝塞尔光束的一般形式,本文所得到的光束可用于构造出更加新型实用的光束.

Phase modulation is an important method of designing accelerating optical beams. In this paper, we present new self-accelerating non-diffracting Bessel-like Hermite-Gaussian beams based on our previous research on Bessel-like beams. The evolutions of the beams along different trajectories are studied numerically and experimentally. These beams are designed by modulating the phase of the initial Hermite-Gaussian beams. With the split-step beam propagation method, we show numerically that (0,1), (1,0), (1,1) and (1,2) modes of the Bessel-like Hermite-Gaussian beams can propagate along different predesigned trajectories. With the computer-generated hologram and spatial light modulator, we observe the propagating behaviors of the Bessel-like Hermite-Gaussian beams along different trajectories, including parabolic, hyperbolic, hyperbolic secant and 3D trajectories. Experimental results show good agreement with the theoretical prediction. It is also demonstrated that the peculiar profile of

研究了部分相干Airy光束在湍流大气中传输时的偏振特性,偏振保持度作为衡量偏振传输效果的一个重要参数.结果表明:部分相干Airy光束在湍流大气中传输足够远时,其偏振度会变回到初始值;而在自由空间中传输,光束的偏振度会保持在某一个特定值;在湍流大气中,当光束传输距离不是很远时,光束对称轴上的偏振度分布为Airy函数,但是当传输足够远时,该偏振度分布逐渐趋向于类高斯状;光束的束腰半径越大,相干长度越长,越有利于光束传输后偏振的保持;存在一个指数截断因子,使得光束的偏振保持度很差.这些结论对于Airy光束在通信领域中的应用具有重要的意义.

The degree of polarization of partially coherent Airy beams propagating through atmospheric turbulence is studied in this paper. Polarization fidelity of the beams is used to judge the propagation effect. It is shown that the degree of polarization of partially coherent Airy beams propagating through atmospheric turbulence tends to its initial value after it has propagated over a sufficient distance, and in free space the degree of polarization retains a certain value. The polarization distribution alone the symmetry axis is an Airy function if the propagation distance is not so long and evolves into a Gaussian-like profile when propagating at sufficient long distance in atmospheric turbulence. The polarization fidelity of the beams with larger waist width ω0 and larger coherence length σ0 is better. There is an exponential truncation factor which badly degrades the polarization fidelity. The results obtained in this paper are very useful for communication of Airy beams.

利用 T 矩阵法研究光镊中微粒大小与入射光束波长相近时，光镊捕获效率与入射光束的阶数、微粒的折射率和尺寸大小的关系．对拉盖尔-高斯光束光镊和高斯光束光镊的轴向和横向捕获效率进行比较．计算结果表明：不同阶数的拉盖尔-高斯光束对微粒捕获效率的影响不同，阶数不超过4的拉盖尔-高斯光束的捕获效率高；微粒半径增加时，拉盖尔-高斯光束的轴向捕获效率逐渐增大，且捕获域也增加，高斯光束的最大捕获效率基本保持不变但捕获域逐渐增大；微粒折射率增加时，拉盖尔-高斯光束和高斯光束的轴向和横向捕获效率均先增加后递减，捕获效率出现了一个峰值，微粒折射率约在1．39～1．69是稳定捕获的最佳数值．

The relationship between optical tweezers trapping efficiency and the orders of the Languerre-Gaussian beams (LG beams),the refractive index and the size of the particles were studied by using T-matrix method.The axial and radial trapping efficiency of optical tweezers of the LG beams and that of the TEM00-mode Gaussian beams were compared.The results show that the trapping efficiency was influenced by the orders of the LG beams.The axial trapping efficiency of the LG beams with orders less than 4 are higher than that of the LG beams with orders more than 4.The axial trapping efficiency and the trapping regions of the LG beams increased with increasing of the particles radii,meanwhile,the axial trapping efficiency of the Gaussian beams almost keeps constant,but the trapping regions increased gradually.The axial and radial efficiency of optical tweezers of the LG beams and the TEM00-mode Gaussian beams increased first and then decreased,with increasing of the refractive indice