与单涡旋光束相比,涡旋光阵列具有多个相位奇点,不仅能够增大信息传输容量,还能增加捕获和观察到的微粒数量。目前在光学领域有多种涡旋光阵列的产生方法,如干涉法、泰伯效应法、光楔衍射法、模式转换法、达曼涡旋光栅法、计算全息法、空间光调制法、超材料图案法等。对这些研究方法的理论模型、实验原理、实验结果及其研究现状进行了详细介绍,并对应用前景作出展望。

在高能激光合成、空间光通信及其他激光工程中的潜在应用方面,阵列涡旋光束逐渐受到人们的关注。基于多重相位屏的数值方法,研究阵列涡旋光束在von Karman湍流中的传输特性,分析了光场的演化情况。结果表明:光束传输一段距离后发生融合,融合后的光束拓扑荷与初始光场中子光束的拓扑荷相同。考虑到光斑扩展会导致拓扑荷的损失进而使得通信效率下降,分析了不同湍流和光束参量对光束相对束宽的影响。湍流强度对相对束宽影响较大,拓扑荷等其他参量均对其有不同程度的影响,相对于单束涡旋光,阵列光束具有更小的相对束宽。

大功率光纤激光器受制于单光纤输出的非线性效应,需要将多个光纤激光器组成光纤激光器阵列进行光束合成,以形成单束聚焦光束,并保证光束在湍流大气中长距离传输后仍可获得高功率、高光束质量的激光输出。以19束激光阵列相干合成系统为例,定量地分析了光束截断因子、角度抖动、湍流传输等因素对相干合成光束的影响,仿真研究了19束激光相干合成的阵列光束的相干传输过程及其在自由空间中的传输特性,用以指导实际激光阵列相干传输系统的建立与运行。

研究了热晕效应对相干合成和非相干合成的列阵平顶光束在大气中传输的影响。结果表明:当列阵平顶光束在大气中传输且存在横向风时,光斑呈月牙状;相干合成时,光斑内存在多个光强峰值;非相干合成时,光斑内始终保持一个峰值;相对于列阵平顶光束的相干合成,非相干合成受热晕的影响较小;光束阶数N越大的列阵平顶光束受热晕的影响越小,即相对于列阵平顶光束,列阵高斯光束(N=1)受热晕的影响更大;光束传输效率在自由空间中随着N的增大而减小,在大气中则随着N的增大而增大;在大气中且功率相同时,列阵平顶光束的传输效率优于列阵高斯光束的传输效率。

在激光驱动惯性约束聚变研究中, 激光等离子体相互作用是影响点火的重要原因之一; 为了抑制激光等离子体的不稳定性, 诸多光束匀滑技术应运而生, 并得到广泛应用。为了获得更匀滑的焦斑, 提出集束多频调制光谱色散匀滑(SSD)技术, 并对其进行了理论研究; 该技术采用多束激光集束聚焦打靶, 利用单频调制单光束, 利用不同的频率调制不同的子束。结果表明, 该技术可以有效抑制多光束干涉导致的强度调制, 改善了远场光强分布的均匀性, 并且在采用更接近实际情况的色循环数时, 具有比传统多频调制SSD技术更好的匀滑效果。

为提高靶面光强，高功率激光驱动装置中常采用多路激光组束打靶，目前主要采用2×2集束的方式。集束聚焦系统中使用的透镜可分为离轴透镜和非离轴透镜,采用非离轴楔形透镜的集束聚焦系统在理想条件下可获得很好的焦斑质量。建立了2×2集束聚焦系统的光传输模型，并仿真研究了实际安装调试过程中各种误差对其焦斑造成的影响。结果表明，反射镜角度和透镜平移对系统的焦斑质量影响很大，需要对其进行精密调试；透镜安装角度和焦距误差对系统的焦斑质量影响较小，现有条件比较容易满足。本文研究可提高研究人员对多光束相干合成集束方案的认识，对实际系统的安装调试有一定指导意义。

Large aperture high-power laser drivers usually focus the high power laser beams in 2×2 quads to the target chamber center in order to increase the light intensity on the target plane. The large aperture wedged focus lenses are the core components in the focus system of quadruplets of beams, and it is thought possible to use four two-dimensional off-axis wedged focus lenses as four sub-lenses to make up a larger aperture wedged focus lens in form to focus the four beams. Given that the large aperture two-dimensional off-axis wedged focus lenses are processed and used difficultly, the wedged focus lenses are divided into three categories: the two-dimensional off-axis wedged focus lenses, the onedimensional off-axis wedged focus lenses, and the non-off-axis wedged focus lenses. On the basis of the three modes of the wedged focus lenses and the corresponding specific incidence angles of each sub-beam, the three focus schemes for the 2×2 beam array are put forward to comparatively research the light intensity distribution on the target plane. Research results show that from a perspective of the coherence among the four sub-beams, the phase factors of each sub-beam respectively introducing by the three focus systems with the two-dimensional off-axis, one-dimensional off-axis, and non-off-axis wedged focus lenses are asymmetric, asymmetric and symmetric inside each sub-beam, and symmetric, asymmetric and symmetric among the four sub-beams. Therefore, the wave front consistency of the four sub-beams decreases in the order of the focus systems with the non-off-axis, two-dimensional off-axis, and one-dimensional off-axis wedged focus lenses. The focus schemes with the non-off-axis wedged focus lenses for 2×2 beam array can get the narrowest main-lobe, the strongest peak-value intensity, the highest energy concentration ratio on the target plane, followed by the one-dimensional off-axis and two-dimensional off-axis wedged focus lenses. The off-axis mode of the wedged focus lenses not only increases the complexity in the course of processing and using, but also increases the main-lobe size, decreases the peak-value intensity and the energy concentration ratio, which obtains a weaker focusing characteristics than that of the non-off-axis mode of the wedged focus lenses. Research results can provide an important reference for the design of the focus system in the target area of high-power laser drivers.