针对高阶正交振幅调制（quadrature amplitude modulation，QAM）信号难以调制分类的问题，提出了一种基于改进型Transformer的深度学习调制分类方法，通过并行2个Transformer的编码器，分析了在加性高斯白噪声（additive white Gaussian noise，AWGN）信道下，从4 QAM到4 096 QAM的10种调制格式在信噪比从−10 dB到30 dB的自动调制分类效果。首先将QAM信号的正交、同相分量提取出来并进行预处理操作，再将预处理过的同相分量和正交分量分别通过2个Transformer编码器来提取分量特征，最后将2个提取到的分量特征进行组合来判断QAM信号的调制格式。实验结果证明：在没有载波频率偏移影响且信噪比大于20 dB时，网络可以准确识别出10种QAM调制格式；在载波频率偏移为500 Hz且信噪比大于26 dB时，网络对10种QAM调制格式的分类准确率高于98.6%。

目前电力通信业务对承载网络的性能需求不断提高，软件定义光网络（SDON）技术以其开放化和软件化的优势驱动着电力通信与SDON技术的融合，基于传统光传输网建立的指标体系和评估方法无法体现SDON架构的特点和对电力通信网业务承载性能的影响。文章结合电力通信业务的性能需求、影响因素及不同SDON架构对业务性能的影响构建了新的指标体系，根据指标对各属性的贡献度确定决策矩阵，提出有序加权平均—扩展逼近理想解排序（OWA-E-TOPSIS）的多属性决策方法，实现了指标的筛选；用层次分析法（AHP）对筛选出的指标进行权重分配，搜集实例，经效用函数法预处理后，进行指标值聚合，通过对比各实例的评估结果，验证了指标体系和评估方法的可行性，为电力通信网新技术的应用和新业务的支撑提供了依据。

An all-fiberized random distributed feedback Raman fiber laser (RRFL) with LP11 mode output at 1134 nm has been demonstrated experimentally, where an intracavity acoustically induced fiber grating is employed for modal switching. The maximum output power of LP11 mode is 93.8 W with the modal purity of 82%, calculated by numerical mode decomposition technology based on stochastic parallel-gradient descent algorithm. To our best knowledge, this is the highest output power with high purity of LP11 mode generated from the RRFL. This work may pave a path towards advanced fiber lasers with special temporal and spatial characteristics for applications.

In this work, a confined-doped fiber with the core/inner-cladding diameter of 40/250 μm and a relative doping ratio of 0.75 is fabricated through a modified chemical vapor deposition method combined with the chelate gas deposition technique, and subsequently applied in a tandem-pumped fiber amplifier for high-power operation and transverse mode instability (TMI) mitigation. Notably, the impacts of the seed laser power and mode purity are preliminarily investigated through comparative experiments. It is found that the TMI threshold could be significantly affected by the seed laser mode purity. The possible mechanism behind this phenomenon is proposed and revealed through comprehensive comparative experiments and theoretical analysis. Finally, a maximum output power of 7.49 kW is obtained with the beam quality factor of approximately 1.83, which is the highest output power ever reported in a forward tandem-pumped confined-doped fiber amplifier. This work could provide a good reference and practical solution to improve the TMI threshold and realize high-power high-brightness fiber lasers.

We found the beam quality factor M² of the fundamental mode as a function of wavelength is U-shaped in the working photonic bandgap (PBG) of an all-solid PBG fiber (AS-PBGF) for the first time, to the best of our knowledge, and our simulation results also match well with the phenomenon. The normal band that is near the high-frequency edge of the third PBG integrates the lowest M² and single-mode operation simultaneously, while the other two edge regions suffer from anomalous variation of M² versus wavelength. The general applicability of this finding can be further extended to other PBGs and also other representative structures in the AS-PBGF field.

High-power mode-programmable orbital angular momentum (OAM) beams have received substantial attention in recent years. They are widely used in optical communication, nonlinear frequency conversion, and laser processing. To overcome the power limitation of a single beam, coherent beam combining (CBC) of laser arrays is used. However, in specific CBC systems used to generate structured light with a complex wavefront, eliminating phase noise and realizing flexible phase modulation proved to be difficult challenges. In this paper, we propose and demonstrate a two-stage phase control method that can generate OAM beams with different topological charges from a CBC system. During the phase control process, the phase errors are preliminarily compensated by a deep-learning (DL) network, and further eliminated by an optimization algorithm. Moreover, by modulating the expected relative phase vector and cost function, all-electronic flexible programmable switching of the OAM mode is realized. Results indicate that the proposed method combines the characteristics of DL for undesired convergent phase avoidance and the advantages of the optimization algorithm for accuracy improvement, thereby ensuring the high mode purity of the generated OAM beams. This work could provide a valuable reference for future implementation of high-power, fast switchable structured light generation and manipulation.