涡旋光束是一种携带轨道角动量的新型结构光场，在超大容量光通信、遥感探测等领域有着广阔的应用前景。涡旋光束在大气等非均匀介质中传输时会产生波前畸变，使得其携带的轨道角动量发生改变，对实际应用产生不利影响，因此需要引入自适应光学波前校正技术对其进行畸变校正。综述了近年来国内外学者在涡旋光束自适应畸变校正方面的研究进展，首先简要介绍了当前较为成熟的涡旋光束畸变校正技术，包括高斯光束探针与波前传感相结合、相位恢复算法与面阵探测技术相结合等技术方案；然后着重介绍了基于深度学习的新型涡旋光束畸变校正技术，包括泽尼克多项式系数反演、湍流相位屏反演等，同时讨论了将深度学习用于涡旋光束畸变校正的优势及局限性；最后展望了涡旋光束自适应畸变校正技术的发展趋势。

作为新型结构光束的一类，全庞加莱球光束因其横截面上自旋角动量和轨道角动量发生耦合，近年来在自由空间光通信领域内受到广泛关注。然而，传输信道中的大气湍流将产生诸如光束扩展、漂移、光强闪烁等严重影响，进而限制光通信系统性能。结合随机相位屏，对具有“C”型偏振奇点的全庞加莱球光束、“V”型偏振奇点的柱矢量光束和均匀偏振的标量涡旋光束在湍流大气中的传播进行大量的数值模拟。归一化光强相关系数和模式纯度被用于研究杂合庞加莱球表面不同位置处表征的全庞加莱球的稳定性。结果表明，相较于具有相似偏振拓扑荷和光强分布的柱矢量光束以及标量涡旋光束而言，坐标位于南半球的全庞加莱球光束在弱湍流和中湍流(r₀=0.5 m, 0.125 m)下具有较高稳定性。而在强湍流下(r₀=0.056 m)，优势区域缩小至2σ∈[−5π/32, 0](纬度坐标)。上述结果将为自由空间远距离通信中传输介质的选取提供重要依据并进一步促进通信质量的提升。

自Allen等证明具有螺旋相位波面的激光束携带有轨道角动量以来，对光束轨道角动量调控技术的研究取得了跨越式的发展，获得了包括相位涡旋光束、矢量涡旋光束、激光束阵列等多种新型结构光场，在超大容量光通信、遥感探测、激光加工、高分辨率成像等领域展现出广阔的应用前景。准确测量光束的轨道角动量是其应用的重要基础，早期人们更多地关注对待测光束所包含的轨道角动量成分分布的测量，后来逐步拓展至对各个轨道角动量成分的强度比重即轨道角动量谱的测量。文中系统地回顾并总结近年来光束轨道角动量谱测量技术的发展，主要介绍了包括基于衍射、模式分束等方法的新型光束轨道角动量谱测量技术。

In this paper, we demonstrate a scheme to tailor both longitudinal and transverse modes inside a laser cavity and constitute an eye-safe single longitudinal mode Er:Y3Al5O12 (Er:YAG) vector laser. A q-plate is employed as a spin-orbital conversion element to modulate the transverse mode and obtain cylindrical vector beams. An optical isolator is employed as a non-reciprocal element for the ring cavity to enforce unidirectional operation and achieve single longitudinal oscillation. The characteristics of power, transverse intensity, and polarization spectrum of the output beams are observed. The observed typical single longitudinal mode and highly matched special polarizations prove the successful tailoring of both longitudinal and transverse modes.

We experimentally demonstrated an approach to generate arbitrary total angular momentum (TAM) states by using two liquid crystal devices. Photons’ TAM, the sum of spin and orbital angular momenta (SAM and OAM) under paraxial approximation, has found many applications in optics and attracted increasing attention in recent years. Our approach is based on the orthogonality of two eigen SAM components, that arbitrary TAM states will be produced through encoding different holograms in one system. The comparison with theoretical predications yields an excellent agreement, including both the separable state and the non-separable state. The proposed scheme takes a step forward for generating complex structured fields and broadens its application to various fields like laser processing and large capacity data transmission.

Multi-ring optical vortices are a kind of structured beams that carry orbital angular momentum (OAM) and have concentrical doughnut intensity distributions. In this Letter, we present both theoretically and experimentally a scheme that employs the dimensions of both the OAM states and radial index of multi-ring optical vortices simultaneously to accomplish high-dimensional free-space data coding/decoding transmissions. Such a scheme can further improve the coding efficiency when limited OAM states are available. In the proof-of-concept experiment, 64-ary coding/decoding employing 16 OAM states and four radial indices are present. Also, the coding/decoding performance when facing various atmosphere turbulences is evaluated. Furthermore, a 64 × 64 gray image (totally, 32,768 bits) is also transmitted through multi-ring optical vortices coding in free-space successfully, showing good transmission performance.