偏振是光的固有自由度，偏振探测提供了光强和波长之外的更多丰富信息。红外偏振探测器在成像、通信、遥感和宇宙学等众多应用中发挥着至关重要的作用。然而，传统的偏振检测系统体积庞大、系统复杂，阻碍了偏振探测的小型化和集成化。近来，片上红外偏振探测器的发展引起了广泛的研究兴趣。本文将重点介绍片上红外偏振探测器的两个前沿研究领域：偏振敏感材料和偏振选择性光耦合结构集成的红外偏振探测器，主要讨论片上红外偏振探测器的研究现状以及未来的挑战和机遇。

High-performance germanium photodiodes are crucial components in silicon photonic integrated circuits for large-capacity data communication. However, the bandwidths of most germanium photodiodes are limited by the intractable resistance–capacitance parasitic effect. Here, we introduce a unique U-shaped electrode to alleviate this issue, reducing the parasitic effect by 36% without compromising any other performance. Experimentally, a large bandwidth of 103 GHz, an optical responsivity of 0.95 A/W at 1550 nm, and a dark current as low as 1.3 nA are achieved, leading to a record high specific detectivity. This is the first breakthrough to 100 GHz bandwidth among all vertical germanium photodiodes, to the best of our knowledge. Open eye diagrams of 120 Gb/s on-off keying and 200 Gb/s four-level pulse amplitude signals are well received. This work provides a promising solution for chip-based ultra-fast photodetection.

文中基于量子阻抗洛伦兹振子（Quantum Impedance Lorentz Oscillator, QILO）模型，研究了含芴二茂铁衍生物的单、双、及三光子吸收特性。首先，理论推导并给出了用有效量子数、电子电量及质量和玻尔半径等微观量表示的该振子四、五阶非线性效应参量的计算参考公式。在此基础上，利用QILO模型，通过拟合取代基为R=NO₂的含芴二茂铁衍生物分子线性吸收光谱，得到了其在400 nm峰值附近的电子跃迁前后的有效量子数，并进一步推算了该分子的双、三光子吸收截面。数值计算结果显示：该化合物分子在793 nm波长附近的双光子吸收截面为 $0.49\times {10}^{-20}\;{\mathrm{c}\mathrm{m}}^{4} \cdot {\mathrm{G}\mathrm{W}}^{-1}$，在1 260 nm和1 314 nm附近的三光子吸收截面分别为 $2.01 \times {10}^{-25}\;{\mathrm{c}\mathrm{m}}^{6}\cdot{\mathrm{G}\mathrm{W}}^{-2}$、 $1.00\times {10}^{-25}\;{\mathrm{c}\mathrm{m}}^{6} \cdot {\mathrm{G}\mathrm{W}}^{-2}$，与实验结果均吻合较好。文中结果说明：QILO模型可以较好地描述以NO₂作为取代基的含芴二茂铁衍生物的单、双、及三光子的吸收特性。根据QILO模型的“依据介质的线性吸收光谱可以估算其多光子吸收截面”的特点，该模型或许能为寻找具有大的双、三光子吸收截面的材料提供一种可供参考的理论分析方法，降低研究多光子过程的综合实验成本。

This work demonstrates the generation of short pulse duration and high-beam-quality laser pulses using transient stimulated Brillouin scattering at a high repetition rate. Thermal effects and optical breakdown are identified as the main factors that restrict energy reflectivity and beam quality under high repetition rates and transient situations. Through experimental analysis, the interaction length and focal point size are determined to be the key parameters in reducing the thermal effect by reducing the absorption of the laser pulse by the medium. The obtained results show that pulses with a duration of 175 ps and beam quality M² of around 1.2 can be achieved with a maximum energy reflectivity of over 40% under an interaction length of 50 mm. Furthermore, at an interaction length of 90 mm, a pulse output with a minimum duration of 115 ps (0.5τ_Q) is achieved.

1.6 µm附近波段激光不仅属于人眼安全波段，而且处于大气传输窗口，不仅如此，高重频、大能量的1.6 µm附近波段激光还可携带高分辨率、大数据量的信息远距离传输。近年来随着晶体制备和镜片镀膜工艺的提高，通过直接泵浦增益介质和频率转换技术获得1.6 µm附近波段的激光在重复频率、能量和光束质量等方面都得到了很大进展。首先，介绍了直接泵浦掺Er³⁺晶体、受激拉曼频移和光参量振荡产生1.6 µm附近波段激光的原理和研究进展；其次，总结了三种方案在获得1.6 µm附近波段激光的优点和缺点；最后，分析了它们在获得高重频、大能量1.6 µm附近波段激光的应用前景。针对光参量振荡输出激光光束质量较差的问题，文中进行分析并给出相应解决方法，最后对通过光参量振荡获得较好光束质量、高重频、大能量1.6 µm附近波段激光的发展前景进行了展望。

亚纳秒激光因其对光电器件的损伤优于纳秒激光和飞秒激光，而被广泛应用于光电对抗领域。然而，在常规水冷条件下实现输出数百赫兹焦耳级亚纳秒激光还面临较大的挑战。笔者课题组面向**重大需求，结合端面泵浦微片晶体百皮秒激光产生技术和多程多级板条激光放大技术，对板条激光器的放大性能进行大量的实验研究，并提出了温控双端泵浦技术，弥补双端泵浦结构的缺陷。实现板条激光器单脉冲能量952 mJ，重复频率500 Hz的激光输出，这将为光电对抗系统所需的高重频大能量激光提供优质光源。

In recent years, optical modulators, photodetectors, (de)multiplexers, and heterogeneously integrated lasers based on silicon optical platforms have been verified. The performance of some devices even surpasses the traditional III-V and photonic integrated circuit (PIC) platforms, laying the foundation for large-scale photonic integration. Silicon photonic technology can overcome the limitations of traditional transceiver technology in high-speed transmission networks to support faster interconnection between data centers. In this article, we will review recent progress for silicon PICs. The first part gives an overview of recent achievements in silicon PICs. The second part introduces the silicon photonic building blocks, including low-loss waveguides, passive devices, modulators, photodetectors, heterogeneously integrated lasers, and so on. In the third part, the recent progress on high-capacity silicon photonic transceivers is discussed. In the fourth part, we give a review of high-capacity silicon photonic networks on chip.

Lithium niobate (LN) has experienced significant developments during past decades due to its versatile properties, especially its large electro-optic (EO) coefficient. For example, bulk LN-based modulators with high speeds and a superior linearity are widely used in typical fiber-optic communication systems. However, with ever-increasing demands for signal transmission capacity, the high power and large size of bulk LN-based devices pose great challenges, especially when one of its counterparts, integrated silicon photonics, has experienced dramatic developments in recent decades. Not long ago, high-quality thin-film LN on insulator (LNOI) became commercially available, which has paved the way for integrated LN photonics and opened a hot research area of LN photonics devices. LNOI allows a large refractive index contrast, thus light can be confined within a more compact structure. Together with other properties of LN, such as nonlinear/acousto-optic/pyroelectric effects, various kinds of high-performance integrated LN devices can be demonstrated. A comprehensive summary of advances in LN photonics is provided. As LN photonics has experienced several decades of development, our review includes some of the typical bulk LN devices as well as recently developed thin film LN devices. In this way, readers may be inspired by a complete picture of the evolution of this technology. We first introduce the basic material properties of LN and several key processing technologies for fabricating photonics devices. After that, various kinds of functional devices based on different effects are summarized. Finally, we give a short summary and perspective of LN photonics. We hope this review can give readers more insight into recent advances in LN photonics and contribute to the further development of LN related research.