Although visible femtosecond lasers based on nonlinear frequency conversion of Ti:sapphire femtosecond oscillators or near-infrared ultrafast lasers have been well developed, limitations in terms of footprint, cost, and efficiency have called for alternative laser solutions. The fiber femtosecond mode-locked oscillator as an ideal solution has achieved great success in the 0.9 to 3.5 μm infrared wavelengths, but remains an outstanding challenge in the visible spectrum (390 to 780 nm). Here, we tackle this challenge by introducing a visible-wavelength mode-locked femtosecond fiber oscillator along with an amplifier. This fiber femtosecond oscillator emits red light at 635 nm, employs a figure-nine cavity configuration, applies a double-clad Pr^{3 +} -doped fluoride fiber as the visible gain medium, incorporates a visible-wavelength phase-biased nonlinear amplifying loop mirror (PB-NALM) for mode locking, and utilizes a pair of customized high-efficiency and high-groove-density diffraction gratings for dispersion management. Visible self-starting mode locking established by the PB-NALM directly yields red laser pulses with a minimum pulse duration of 196 fs and a repetition rate of 53.957 MHz from the oscillator. Precise control of the grating pair spacing can switch the pulse state from a dissipative soliton or a stretched-pulse soliton to a conventional soliton. In addition, a chirped-pulse amplification system built alongside the oscillator immensely boosts the laser performance, resulting in an average output power over 1 W, a pulse energy of 19.55 nJ, and a dechirped pulse duration of 230 fs. Our result represents a concrete step toward high-power femtosecond fiber lasers covering the visible spectral region and could have important applications in industrial processing, biomedicine, and scientific research.

甚宽视场相机作为高分六号卫星的核心载荷，具备65.6°视场、862 km超大幅宽和8谱段成像能力。针对其自由曲面离轴四反光学系统的结构特点和任务需求，采用复合型多层隔热组件进行热隔离、高导热率石墨膜进行热疏导及分级热控等措施进行了热控设计，实现了光机结构的精密控温和高热耗/热流密度电子学设备的高效散热，并利用有限元分析软件UG12.0/Space thermal仿真分析了相机高、低温工况下的温度；通过对比热分析、热试验及卫星在轨遥测温度数据，验证了该热控方案的实际效果。在轨遥测数据显示：光机结构在轨温度水平为19.7~20.3 ℃，温度梯度最大不超过0.4 ℃，CMOS焦面组件每轨摄像12 min的情况下，温度波动在19~24 ℃，均满足热控指标要求，遥测数据与热分析及热试验结果偏差小于±0.5 ℃。表明该相机热设计正确可行，热分析及热试验过程合理可靠。

Metallic few-layered 1T phase vanadium disulfide nanosheets have been employed for boosting sodium ion batteries. It can deliver a capacity of 241 mAh?g^?1 at 100 mA?g^?1 after 200 cycles. Such long-term stability is attributed to the facile ion diffusion and electron transport resulting from the well-designed two-dimensional (2D) electron-electron correlations among V atoms in the 1T phase and optimized in-planar electric transport. Our results highlight the phase engineering into electrode design for energy storage.

完美涡旋（POV）光束具有光束半径与拓扑荷数无关的特点，与其他涡旋光束相比具有更加稳定的空间强度分布特性。利用多相位屏法和傅里叶变换法，分析了POV光束在大气湍流中的斜程传输特性。采用光束漂移和孔径平均闪烁指数作为大气湍流影响光束质量的评价参数，对比了POV光束与高斯涡旋光束在相同传输条件下的光束质量。结果表明：相比于高斯涡旋光束，POV光束的光束稳定性更好。当拓扑荷数增大或天顶角减小时，POV光束抵抗大气湍流的能力增强。在不改变POV光束拓扑荷数的前提下增大其光束半径，也能提高POV光束对大气湍流的抵抗能力。

We have successfully generated a 1.3/1.4 µm random fiber laser (RFL) using bismuth (Bi)-doped phosphosilicate fiber. The Bi-doped RFL has shown excellent long-term operational stability with a standard deviation of approximately 0.34% over 1 h at a maximum output power of 549.30 mW, with a slope efficiency of approximately 29.21%. The Bi-doped phosphosilicate fiber offers an emission spectrum ranging from 1.28 to 1.57 µm, indicating that it can be tuned within this band. Here, we demonstrated a wavelength-tuning fiber laser with a wavelength of 1.3/1.4 µm, achieved through the using of a fiber Bragg grating or a tunable filter. Compared to traditional laser sources, the RFL reduces the speckle contrast of images by 11.16%. Due to its high stability, compact size, and high efficiency, this RFL is highly promising for use in biomedical imaging, communication, and sensor applications.

High-energy pulsed lasers in the green spectral region are of tremendous interest for applications in space laser ranging, underwater detection, precise processing, and scientific research. Semiconductor pulsed lasers currently are difficult to access to the so-called “green gap,” and high-energy green pulsed lasers still heavily rely on the nonlinear frequency conversion of near-IR lasers, precluding compact and low-cost green laser systems. Here, we address this challenge by demonstrating, for the first time to the best of our knowledge, millijoule-level green pulses generated directly from a fiber laser. The green pulsed fiber laser consists of a 450 nm pump laser diode, a Ho3+-doped ZBLAN fiber, and a cavity-dumping module based on a visible wavelength acousto-optic modulator. Stable pulse operation in the cavity-dumping regime at 543 nm is observed with a tunable repetition rate in a large range of 100 Hz–3 MHz and a pulse duration of 72–116 ns. The maximum pulse energy of 3.17 mJ at 100 Hz is successfully achieved, which is three orders of magnitude higher than those of the rare-earth-doped fiber green lasers previously reported. This work provides a model for compact, high-efficiency, and high-energy visible fiber pulsed lasers.