柱矢量光束因其独特的偏振分布特性而在光镊、高分辨率成像、遥感、等离子体聚焦等领域发挥着重要作用。为实现全光纤高功率柱矢量MOPA激光器，采用自主设计基于集成超表面的模式转换光纤器件，进行了理论分析与实验验证。自主设计集成超表面的模式转换光纤器件可直接稳定输出数瓦功率的径向偏振柱矢量种子光，且输出模式纯度可达95%以上。实验中通过降低弯曲损耗并对模式进行控制，获得了单级放大输出功率为52.2 W的径向偏振柱矢量光稳定输出，且模式光场分布在输出功率增加过程中并未出现明显变化。为进一步分析输出的模式特性，采用旋转检偏器的方法检测输出光的偏振特性及偏振纯度，并利用非相干模式叠加方法计算了输出的径向偏振柱矢量光的模式纯度。结果表明，集成超表面模式转换的全光纤柱矢量MOPA激光器在最大输出功率情况下，输出光的偏振纯度约为95.2%，模式纯度约为94%，验证了该全光纤方案的可行性。

A high-energy 100-Hz optical parametric oscillator (OPO) based on a confocal unstable resonator with a Gaussian reflectivity mirror was demonstrated. A KTA-based OPO with a good beam quality was obtained when the magnification factor was 1.5, corresponding to the maximum signal (1.53 µm) energy of 56 mJ and idler (3.47 µm) energy of 20 mJ, respectively. The beam quality factors (M²) were measured to be M²_x = 5.7, M²_y = 5.9 for signal and M²_x = 8.4, M²_y = 8.1 for idler accordingly. The experimental results indicated that the beam quality positively changed with the increase of magnification factors, accompanied by an acceptable loss of pulse energy.

Re:YAG-SiO₂多组分玻璃光纤是以Re:YAG作为纤芯材料，以石英管作为包层材料，采用熔芯法利用拉丝塔在高温下拉制的特种光纤，具有掺杂浓度高、增益大、机械强度高、易与石英光纤熔接等优点，适用于短腔单频光纤激光器。文中介绍了Re:YAG-SiO₂光纤的制备工艺，结合笔者课题组在该领域的研究工作，综述了近年来基于Re:YAG-SiO₂光纤的单频激光技术在1.0 μm，1.5 μm及2.0 μm波段的研究进展，并对Re:YAG-SiO₂光纤的制备及基于该类光纤单频激光器所存在的问题进行了归纳分析，对未来的发展进行了展望。

Beam quality improvements by a large margin for signal and idler beams of a high energy 100 Hz KTiOAsO4 (KTA) non-critical phase matching (NCPM) optical parametric oscillator (OPO) were demonstrated using an unstable resonator configuration instead of a plane-parallel one. Theoretically, influences of cavity lengths and transmission of an output coupler on the OPO conversion efficiency for both were numerically simulated. For OPO based on an unstable resonator with a Gaussian reflectivity mirror, the maximum pulse energies at the signal (1.53 µm) and idler (3.47 µm) were about 75 mJ and 26 mJ, respectively. The corresponding beam quality factors of the signal were M_x² = 9.8 and M_y² = 9.9, and M_x² = 11.2 and M_y² = 11.5 for the idler. As a comparison, 128 mJ of signal and 48 mJ of idler were obtained with the plane-parallel resonator, and the M² factors of the signal were M_x² = 39.8 and M_y² = 38.4, and M_x² = 32.1 and M_y² = 31.4 for the idler. Compared with a plane-parallel cavity, over eight times and three times brightness improvements were realized for the signal and idler light, respectively.

An actively mode-locked fiber laser with controllable pulse repetition rate and tunable pulse duration is presented, in which an optical delay line (ODL) is used to adjust the cavity length precisely for regulating the repetition rate, and a semiconductor optical amplifier (SOA) is introduced for enabling the pulse duration control. Experimentally, continuous tuning of the repetition rate from 2 GHz to 6 GHz is realized, which is limited by the availability of an even higher repetition rate radio-frequency (RF) source. Specifically, when the repetition rate is fixed at 2.5 GHz, the pulse duration can be tuned from 4 ps to 30 ps, which is, to the best of our knowledge, the widest tuning range of pulse duration ever achieved in a gigahertz (GHz) repetition rate actively mode-locked 1.5 µm fiber laser oscillator.