由于自激振荡的限制，单级超荧光光纤光源的功率提升十分困难，目前仅达到百瓦量级。基于主振荡功率放大（MOPA）方案，使用1018 nm光纤激光级联泵浦1080 nm波段的超荧光，实现了6.2 kW高功率输出。最高功率下的光光转换效率为81.5%，没有出现横模不稳定（TMI），功率提升受限于受激拉曼散射（SRS）。

级联泵浦方案具有泵浦光亮度高、量子亏损小、光纤热负荷低、模式不稳定阈值高等优势，是获得高功率光纤激光的主要技术方案。目前，万瓦级高光束质量光纤激光的实现在非线性效应抑制和模式控制等方面遇到困难。本文介绍了国防科技大学近年来在高光束质量级联泵浦光纤激光器方面的研究进展，并对功率和光束质量进一步提升的可行途径进行了分析。

设计了一种无偏振片液晶透镜的离焦深度测量（DFD）方法。分别建立液晶透镜成像下的o光和e光的高斯模糊退化模型，将其加权求和得到自然光在液晶透镜成像下的模糊退化模型，求取自然光和e光下深度估计对噪声的偏导，并进行数值仿真，结果表明，自然光模型比e光模型抗干扰能力更强，小模糊光斑比大模糊光斑抗干扰能力更强。在无偏模糊均衡滤波器（UDE）算法的基础上，利用导向滤波对偏差进行滤波，并对置信度模型进行修正，引入实例分割对估计结果进行优化。搭建了放大率恒定的液晶透镜光学成像系统，实现了自然光条件下利用液晶透镜的深度测量。实验结果表明，本文方案和e光条件下UDE方法相比，均方根误差降低了56%。

Integrated photonics provides a promising platform for quantum key distribution (QKD) system in terms of miniaturization, robustness, and scalability. Tremendous QKD works based on integrated photonics have been reported. Nonetheless, most current chip-based QKD implementations require additional off-chip hardware to demodulate quantum states or perform auxiliary tasks such as time synchronization and polarization basis tracking. Here, we report a demonstration of resource-efficient chip-based BB84 QKD with a silicon-based encoder and a decoder. In our scheme, the time synchronization and polarization compensation are implemented relying on the preparation and measurement of the quantum states generated by on-chip devices; thus, we need no additional hardware. The experimental tests show that our scheme is highly stable with a low intrinsic quantum bit error rate of 0.50%±0.02% in a 6 h continuous run. Furthermore, over a commercial fiber channel up to 150 km, the system enables the realization of secure key distribution at a rate of 866 bit/s. Our demonstration paves the way for a low-cost, wafer-scale manufactured QKD system.

Based on the 90 nm silicon photonics commercial foundry, sidewall-doped germanium–silicon photodetectors (PDs) are designed and fabricated. The large designed overlap between the optical field and electric field achieves high responsivity while retaining high-speed performance. Even including the loss due to optical fiber coupling, the PD demonstrates an external responsivity greater than 0.55 A/W for transverse magnetic (TM) polarization and 0.65 A/W for transverse electric (TE) polarization at 1530 nm. A flat responsivity spectrum of >0.5A/W is achieved up to 1580 nm for both polarizations. Their internal responsivities can exceed 1 A/W in the C+L optical communication bands. Furthermore, with the aid of a 200 mm wafer-level test and analysis, the overall PDs of 26 reticles have a 3 dB optoelectrical bandwidth >50GHz and a dark current <10nA at a -3V bias voltage. Finally, the eye diagram performances under TE and TM polarizations, various modulation formats, and different input wavelengths are comprehensively investigated. The clear open electrical eye diagrams up to 120, 130, 140, and 150 Gbit/s nonreturn-to-zero are experimentally attained at a photocurrent of 1 mA. To the best of our knowledge, this is the first time that single-lane direct detection of record-high-speed 200, 224, 256, and 290 Gbit/s four-level pulse amplitude modulation (PAM) and 300, 336, 384, and 408 Gbit/s eight-level PAM optical signals has been experimentally achieved.

人工神经网络（ANN）学科的发展推动了信息处理技术的进步，目前，被称为第3代ANN的脉冲神经网络（SNN）以其更具生物可解释性，更适合ANN硬件实现的优势受到业界的广泛关注，并已成功应用于模式识别、医学成像和智能控制等多个领域。受制于“后摩尔时代”电子芯片的制程不断接近极限以及冯·诺依曼体系“存算分离”带来的性能瓶颈，低时延、低能耗、高带宽和高并行性的光子计算方案应用于SNN的硬件实现成为信息处理领域多学科融合的热门课题。文章介绍了光子SNN的起源，利用光学器件的特性实现神经元的行为和突触连接强度的变化进而实现SNN的研究历程和多种实现方案，总结了光子SNN目前存在的瓶颈和挑战，展望了光子SNN的未来发展趋势。

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.

实现万瓦级高光束质量光纤激光面临模式控制和非线性效应抑制等技术难题。为兼顾光束质量和功率，设计了基于纤芯直径为30 μm、包层直径为250 μm的双包层掺镱光纤的后向级联泵浦激光器，实现了输出功率为10.03 kW、M²因子为1.92、拉曼抑制比大于38 dB的激光输出，实现万瓦级光纤激光器的光束质量M²优于2，这验证了常规双包层光纤具有支撑万瓦高光束质量激光产生和放大能力。