Ex situ characterization techniques in molecular beam epitaxy (MBE) have inherent limitations, such as being prone to sample contamination and unstable surfaces during sample transfer from the MBE chamber. In recent years, the need for improved accuracy and reliability in measurement has driven the increasing adoption of in situ characterization techniques. These techniques, such as reflection high-energy electron diffraction, scanning tunneling microscopy, and X-ray photoelectron spectroscopy, allow direct observation of film growth processes in real time without exposing the sample to air, hence offering insights into the growth mechanisms of epitaxial films with controlled properties. By combining multiple in situ characterization techniques with MBE, researchers can better understand film growth processes, realizing novel materials with customized properties and extensive applications. This review aims to overview the benefits and achievements of in situ characterization techniques in MBE and their applications for material science research. In addition, through further analysis of these techniques regarding their challenges and potential solutions, particularly highlighting the assistance of machine learning to correlate in situ characterization with other material information, we hope to provide a guideline for future efforts in the development of novel monitoring and control schemes for MBE growth processes with improved material properties.

面向核电磁脉冲等强电磁环境下复合材料壳体平台的电磁环境效应分析需求，根据Maxwell-Ampere定理的积分形式，分析得到了时域有限差分方法在处理弱导电薄层介质材料参数时的等效计算方法，即当介质等效波长远大于模型厚度时，可将薄层模型适当增厚，同时等比例减小其电导率，参数等效前后模型的电磁耦合特性基本相同。该方法通过等效增厚薄层材料从而实现增大空间离散步长，减少网格量的目的，不需要改变传统时域有限差分方法的时间步进格式，不会破坏计算的稳定性。无限大有耗介质薄板、薄层球体、含薄层壳体无人机电磁耦合等算例表明，在包含毫米级厚度弱导电介质薄层壳体平台的核电磁脉冲耦合模拟中，该方法具有较好的适用性。

为了消除激光诱导击穿光谱技术（laser-induced breakdown spectroscopy，LIBS）中的自吸收效应，提高元素定量分析的精确度，同时满足工业中便捷分析元素的要求，需将自吸收免疫激光诱导击穿光谱技术（self-absorption free laser-induced breakdown spectroscopy，SAF-LIBS）的装置小型化。本文提出了一项新型的高重频声光门控SAF-LIBS定量分析技术，使用高重频激光器产生准连续的等离子体以增强光谱强度，并将声光调制器（acousto-optic modulator，AOM）作为门控开关，从而使微型CCD光谱仪和AOM能够代替传统大型SAF-LIBS装置中的像增强探测器（intensified charge coupled device，ICCD）和中阶梯型光栅光谱仪，实现自吸收免疫的同时缩小了装置的体积，降低了装置的成本。将该系统参数进行优化选择后，对样品中的Al元素进行了定量分析和预测。实验结果表明，等离子体的特性受激光重复频率的影响进而会影响光谱信号的强度。在1 ~ 50 kHz激光重复频率范围内，Al I 394.4 nm和Al I 396.15 nm的双线强度先增强后减弱，确定最佳的激光重复频率为10 kHz。在不同的光纤采集角度下，Al的双线强度比随延迟时间的增加而减小，在45°处信噪比最高，且在一定的积分时间下，最佳光学薄时间t_ot为426 ns。在激光重复频率为10 kHz、光纤采集角为45°、延迟时间为400 ns的条件下，对Al元素进行定量分析和预测结果表明，Al元素定标曲线的线性度R²为0.982，平均绝对测量误差相对于单一LIBS的0.8%可以降低至0.18%。定量分析结果与传统大型SAF-LIBS装置的测量精度相持平。因此本高重频声光门控SAF-LIBS装置不仅有效地屏蔽了光学厚等离子体中的连续背景辐射和谱线加宽，同时具备小型化、低成本、高可靠性的优点，有助于推动SAF-LIBS技术由实验室走向工业应用。

为了实现窄带完美吸收，本文提出了一种简单的三层金-二氧化硅-金薄膜(MDM)结构。通过电磁波时域差分算法(FDTD)进行模拟仿真和理论计算，详细分析了该结构的可调谐吸收特性，同时建立了理论模型，分析了其中存在的电磁模式以及窄带完美吸收的物理机制。首先，利用电磁波时域差分算法和传输矩阵算法(TMM)对该结构进行了理论计算，详细地分析了各个结构参数对吸收光谱的影响。然后，对该结构形成的窄带完美吸收物理机制进行了分析讨论。最后，利用磁控溅射制备手段，成功制备了三层结构的样片。实验观测到的结果与理论仿真一致。实验结果表明：本文提出的窄带完美吸收结构，最窄带宽约为21 nm，最高吸收可达99.51%，基本实现了窄带完美吸收。本文研究成果为相关应用奠定了基础。

近年来，杂化钙钛矿半导体材料由于其带隙可调、吸收系数高、载流子迁移率高、成本低廉等诸多优点，在光电器件领域备受青睐，如太阳能电池、电致发光器件、光电探测器等。其中，钙钛矿单晶薄膜因其无晶界、杂质和缺陷含量低等特点，展现出更为优异的光学、电学特性，成为制备高性能光电器件的理想材料体系。然而，钙钛矿单晶薄膜常采用空间限域法直接生长在空穴传输层上，不可避免地将导致界面缺陷和载流子层间输运等问题，严重制约了钙钛矿单晶薄膜光电探测器的性能。为此，本文通过引入模板剥离法工艺技术，在钙钛矿单晶薄膜两侧分别蒸镀功能层材料，制备了结构为Cu/BCP/C₆₀/MAPbBr₃/MoO₃/Ag的钙钛矿单晶薄膜光电探测器。基于模板剥离法，两侧蒸镀的功能层与钙钛矿单晶薄膜接触紧密，将有效改善载流子的注入和传输；同时，优化的器件结构以及考虑能带匹配等因素可实现高灵敏、响应快速的钙钛矿单晶薄膜光电探测器。改进后器件的开关比高达3.1 × 10³，响应度可达7.15 A/W，探测率为5.39 × 10¹² Jones，外量子效率达到1794%。该工作为进一步改善和提升钙钛矿单晶薄膜光电探测器的探测性能提供了一种可行性技术方案。

We present an effective approach to realize a highly efficient, high-power and chirped pulse amplification-free ultrafast ytterbium-doped yttrium aluminum garnet thin-disk regenerative amplifier pumped by a zero-phonon line 969 nm laser diode. The amplifier delivers an output power exceeding 154 W at a pulse repetition rate of 1 MHz with custom-designed 48 pump passes. The exceptional thermal management on the thin disk through high-quality bonding, efficient heat dissipation and a fully locked spectrum collectively contributes to achieving a remarkable optical-to-optical efficiency of 61% and a near-diffraction-limit beam quality with an M² factor of 1.06. To the best of our knowledge, this represents the highest conversion efficiency reported in ultrafast thin-disk regenerative amplifiers. Furthermore, the amplifier operates at room temperature and exhibits exceptional stability, with root mean square stability of less than 0.33%. This study significantly represents advances in the field of laser amplification systems, particularly in terms of efficiency and average power. This advantageous combination of high efficiency and diffraction limitation positions the thin-disk regenerative amplifier as a promising solution for a wide range of scientific and industrial applications.