Lead-free perovskite Cs2AgBiBr6 manifests great potential in developing high-performance, environmentally friendly, solution-processable photodetectors (PDs). However, due to the relatively large energy bandgap, the spectrum responses of Cs2AgBiBr6 PDs are limited to the ultraviolet and visible region with wavelengths shorter than 560 nm. In this work, a broadband Cs2AgBiBr6 PD covering the ultraviolet, visible, and near infrared (NIR) range is demonstrated by incorporating titanium nitride (TiN) nanoparticles that are prepared with the assistance of self-assembled polystyrene sphere array. In addition, an atomically thick Al2O3 layer is introduced at the interface between the Cs2AgBiBr6 film and TiN nanoparticles to alleviate the dark current deterioration caused by nanoparticle incorporation. As a result, beyond the spectrum range where Cs2AgBiBr6 absorbs light, the external quantum efficiency (EQE) of the TiN nanoparticle incorporated Cs2AgBiBr6 PD is enhanced significantly compared with that of the control, displaying enhancement factors as high as 2000 over a broadband NIR wavelength range. The demonstrated enhancement in EQE arises from the photocurrent contribution of plasmonic hot holes injected from TiN nanoparticles into Cs2AgBiBr6. This work promotes the development of broadband solution-processable perovskite PDs, providing a promising strategy for realizing photodetection in the NIR region.

偏振成像技术作为一种新型的光学成像技术，可以实现抑制背景噪声、提高探测距离、获取目标细节特征和识别伪装目标等功能。由于成像空间维度的不同，偏振二维成像和偏振三维成像在不同领域中具有良好的应用前景。文中从偏振光的表示与传播方式入手，先后对偏振成像系统、偏振二维成像技术、偏振三维成像技术和基于超表面偏振器件的偏振探测及成像的研究展开综述。首先，根据偏振成像系统结构的不同，偏振成像系统可分为分时型、分振幅型、分孔径型和分焦平面型四种，并对以上偏振成像系统分别进行详细介绍和比较分析。其次，阐述了基于图像增强技术的偏振二维成像。图像增强技术分为偏振差分算法和图像融合两种。对于偏振三维成像，根据所处理反射光成分的不同，分为基于镜面反射光和漫反射光的偏振三维成像。综述了三维形貌重建过程中天顶角和方位角多值性问题的解决办法。为了高效准确地获取偏振信息，基于超表面结构的偏振器件成为当前研究的热点。进一步介绍了基于超表面偏振器件的偏振探测及成像技术。最后，总结全文并对偏振成像技术的发展前景进行展望。

宽谱响应光电探测器在图像传感和光通信等领域应用前景广阔。金属微纳结构通过激发表面等离激元共振效应可高效产生热载流子，将它们与宽带隙半导体构成异质结构，便可利用热载流子开发出低成本宽谱响应光电探测器。研究设计了一种基于Au/TiO₂复合纳米结构的热电子光电探测器。其中TiO₂层经退火后形成尺度约为百纳米的凹凸结构，Au纳米颗粒层与用作电极的保形Au膜共同组成了激发表面等离激元共振的纳米结构。由于Au/TiO₂复合纳米结构的协同作用，该器件在400~900 nm范围内具有宽谱光吸收性能，器件的平均光吸收效率为33.84%。在此基础上，该器件能够探测TiO₂本征吸收波段以外的入射光子。例如，在600 nm波长处，器件的响应率为9.67 μA/W，线性动态范围为60 dB，器件的上升/下降响应速度分别为1.6 ms和1.5 ms。此外，利用有限元法进行了仿真计算，通过电场分布图验证了Au/TiO₂复合纳米结构中所激发的丰富表面等离激元共振效应是其实现宽谱高效探测的原因所在。

MAPbI3 perovskite has attracted widespread interests for developing low-cost near infrared semiconductor gain media. However, it faces the instability issue under operation conditions, which remains a critical challenge. It is found that the instability of the MAPbI3 nanoplatelet laser comes from the thermal-induced degradation progressing from the surface defects towards neighboring regions. By using PbI2 passivation, the defect-initiated degradation is significantly suppressed and the nanoplatelet degrades in a layer-by-layer way, enabling the MAPbI3 laser to sustain for 4500 s (2.7×107pulses), which is nearly three times longer than that of the nanoplatelet laser without passivation. Meanwhile, the PbI2 passivated MAPbI3 nanoplatelet laser with the nanoplatelet cavity displays a maximum quality factor up to ∼7800, the highest reported for all MAPbI3 nanoplatelet cavities. Furthermore, a high stability MAPbI3 nanoplatelet laser that can last for 8500 s (5.1×107pulses) is demonstrated based on a dual passivation strategy, by retarding the defect-initiated degradation and surface-initiated degradation simultaneously. This work provides in-depth insights for understanding the operating degradation of perovskite lasers, and the dual passivation strategy paves the way for developing high stability near infrared semiconductor laser media.