气密封装是推动电子器件高可靠发展的一项重要技术，传统气密封装技术存在焊接温度高、热冲击大、应用范围窄等问题，无法满足三维电镀陶瓷基板气密封装要求。本文结合脉冲激光焊接的技术优势，研究了脉冲激光焊接三维电镀陶瓷基板实现气密封装，重点探讨了焊接过程中脉冲激光与材料相互作用模式，分析了焊接样品界面微观形貌、气密性、力学性能等。研究表明，焊接金属区裂纹的出现与基底金属铜向可伐侧的扩散密切相关；焊接过程稳定、焊接熔深小的热传导模式和过渡模式可以避免焊接裂纹出现。通过试验优化了焊接工艺参数，当激光峰值功率为120 W、脉冲宽度为1 ms、重叠率为80%时，三维陶瓷基板腔体结构获得了最佳高气密性，泄漏率为5.2×10^-10 Pa·m³/s，接头剪切强度为278.06 MPa，满足第三代半导体器件高可靠气密封装需求。

Topological nodal-line semimetals attract growing research attention in the photonic and optoelectronic fields due to their unique topological energy-level bands and fascinating nonlinear optical responses. Here, to the best of our knowledge, we first report the saturable absorption property of topological nodal-line semimetal HfGeTe and the related pulse modulation in passively Q-switched visible lasers. Few-layer HfGeTe demonstrates outstanding saturable absorption properties in the visible-light band, yielding the saturation intensities of 7.88, 12.66, and 6.64 µJ/cm² at 515, 640, and 720 nm, respectively. Based on an as-prepared few-layer HfGeTe optical switch and a Pr:LiYF₄ gain medium, Q-switched visible lasers are also successfully achieved at 522, 640, and 720 nm. The minimum pulse widths of the green, red, and deep-red pulsed lasers are 150, 125.5, and 420 ns, respectively. Especially for the green and red pulsed laser, the obtained pulse width is smaller than those of the low-dimensional layered materials. Our work sheds light on the application potential of topological nodal-line semimetals in the generation of visible pulsed lasers.

3 μm激光处于分子指纹区，在医疗外科、气体检测、**应用等领域都有重要的应用价值。Er³⁺∶ZBLAN光纤激光器具有效率高、可集成的优点，是3 μm激光的主要输出方式。本文从铒离子跃迁产生3 μm激光出发，围绕Er³⁺∶ZBLAN光纤激光器，介绍了3 μm激光产生的结构原理及能级系统，总结了实现该波段高功率连续输出和脉冲输出的技术方案和研究进展，重点介绍了基于不同材料可饱和吸收体的调Q和锁模激光器实验研究，并对目前实现3 μm波段高功率输出需要解决的问题进行了分析，最后对Er³⁺∶ZBLAN激光器的发展方向进行了展望。

We present a study on a watt-level acousto-optically Q-switched Pr:YLF laser at three different repetition rates (10 kHz, 20 kHz, and 50 kHz) for the first time, to the best of our knowledge. The corresponding average output powers and pulse widths were measured to be 1.14 W, 1.2 W, and 1.32 W, and 40 ns, 52 ns, and 80 ns, respectively. A maximum pulse energy of 0.11 mJ was obtained, corresponding to a peak power of up to 2.8 kW at a repetition rate of 10 kHz. The simulated dynamics of a fast Q-switched Pr:YLF laser is in agreement with the experiment. The laser’s ability to generate stable pulses with high peak power and short pulse width makes it highly desirable for various practical applications, such as laser machining and material processing.

通过提出双电子共振吸收模型，解释了激光与半导体材料相互作用时材料吸收光子的物理机制，分析了温度、掺杂数密度对吸收系数的影响；结合热峰模型，将激光的能量注入视为热源，计算出了激光入射时材料中电子温度的时空演化，通过费米狄拉克分布计算出自由电荷数密度分布，得到了电荷激发过程的计算模型，模拟了激光诱发单粒子翻转的过程。模拟结果表明，激光能量与激发电荷总量的关系是非线性的，这意味着激光能量与粒子的线性能量传输之间为非线性对应关系，与实验结果相符。