High-order dispersion introduced by Gires–Tournois interferometer mirrors usually causes spectral sidebands in the near-zero dispersion region of mode-locked fiber lasers. Here, we demonstrate a sideband-free Yb-doped mode-locked fiber laser with dispersion-compensating Gires–Tournois interferometer mirrors. Both the simulation and the experiment demonstrate that the wavelength and energy of the sidebands can be tuned by changing the transmission coefficient of the output mirror, the pump power, and the ratio of the net cavity dispersion to the net third-order dispersion in the cavity. By optimizing these three parameters, the laser can generate a sideband-free, Gaussian-shaped spectrum with a 13.56-nm bandwidth at -0.0232ps2 net cavity dispersion, which corresponds to a 153-fs pulse duration.

针对轨道交通车辆车体铝合金型材焊接同步激光清洗，开展了相关工艺、测试与应用技术研究。通过工艺研究得出铝合金氧化膜激光清洗工艺窗口，建立了匹配不同焊接速度的激光清洗参数预测模型，并分析了激光清洗对铝合金表面氧化膜的影响；针对实际工况，设计了激光清洗-电弧焊接同步清焊一体化装置，并开展焊接同步激光清洗工艺验证，实现了焊前高质高效去除氧化膜；通过分析焊接接头力学性能，检测焊缝缺陷，观测焊接接头截面微观组织，评判焊接同步激光清洗焊缝质量。研究表明，采用200 W脉冲激光，清洗速度0.5~1.1 m/min可调的情况下，可以实现线宽45 mm的焊接同步氧化膜的有效清洗，经激光清洗后，原生氧化膜被完全去除，且可避免再生氧化膜的影响。经激光清洗后的焊接接头剪切强度及应变相较未处理的接头分别提升了26.4%和9.98%，较人工打磨后的接头强度分别提升了3.53%和1.43%，焊缝中心组织主要由α基体和β （Mg₂Al₃）相组成，焊接性能满足轨道交通车辆车体制造要求，可有效替代人工打磨。

研究了分子束外延生长条件对高铟组分InGaAs材料性能的影响，分析了生长温度、V/III比和As分子束形态对In_0.74Ga_0.26As材料光致发光和X射线衍射峰强度、本底载流子浓度和迁移率的影响。测试结果表明：适中的生长温度和V/III比可以提高材料晶格质量，减少非辐射复合，降低本底杂质浓度。As分子束为As₂时In_0.74Ga_0.26As材料质量优于As₄分子束。当生长温度为570 ℃，As分子束形态为As₂，V/III比为18时，可以获得较高的光致发光和X射线衍射峰强度，室温和77 K下的本底载流子浓度分别达到6.3×10¹⁴ cm^-3和4.0×10¹⁴ cm^-3，迁移率分别达到13 400 cm²/Vs和45 160 cm²/Vs。

目前，飞秒激光脉冲因脉冲宽度窄和峰值功率高的特点被广泛运用在多种领域中。其中，色散管理光纤锁模激光器因其特有的腔内呼吸机制使输出的激光脉冲能量更高，光谱更宽、脉宽更窄。使用啁啾布拉格光纤光栅进行色散管理的光纤锁模激光器能够实现真正的全光纤结构，提升激光器的紧凑性和稳定性，因此基于啁啾布拉格光纤光栅进行色散管理的光纤锁模激光器具有更加实际的应用意义。采用数值模拟的方法，研究了基于啁啾布拉格光纤光栅进行色散管理的掺镱光纤锁模激光器中单模光纤在腔内的不同分布对脉冲动力学过程和输出脉冲参数的影响。系统分析了谐振腔内净色散值不同时，腔内单模光纤的分布对脉冲在腔内的动力学过程的影响。模拟结果表明，在腔内净色散值为负时，啁啾布拉格光纤光栅与增益光纤间的单模光纤越短，光纤激光器维持稳定单脉冲运行的最大泵浦强度更高且输出光谱更宽，从而能够获得脉宽更窄的去啁啾脉冲；腔内净色散值越接近零时，啁啾布拉格光纤光栅与增益光纤间的单模光纤长度对输出脉冲参数作用的影响越显著；腔内净色散值为正时，单模光纤在腔内的分布对输出脉冲影响逐渐减弱，优化单模光纤分布提升锁模激光器性能并不明显。最后，提出了一种通过改变单模光纤在腔内的分布来提高激光器输出性能的优化方法。

Ultrafast lasers with high repetition rate, high energy, and ultrashort pulse duration have enabled numerous applications in science and technology. One efficient route to generate such pulses is postcompression of high-power Yb-doped lasers. Here, we report on the generation of 24.5 fs pulses with an output energy of 1.6 µJ and a repetition rate of 500 kHz. The pulses are obtained by using a hybrid cascaded nonlinear compression of the pulses delivered by a Yb-based fiber chirped pulse amplification (CPA) system. In the first stage, the initial 390 fs laser pulses are compressed to 100.7 fs based on spectral broadening in three fused silica plates. In the second stage, the pulses have been shortened to sub-30 fs by means of nonlinear compression in a hollow-core fiber. Overall, we could achieve ∼16 times temporal shortening with the proposed approach. The results show that our system can effectively generate few-cycle pulses at a relatively high repetition rate and high energy, which can benefit future possible applications.