Mode-locked microcombs with flat spectral profiles provide the high signal-to-noise ratio and are in high demand for wavelength division multiplexing (WDM)-based applications, particularly in future high-capacity communication and parallel optical computing. Here, we present two solutions to generate local relatively flat spectral profiles. One microcavity with ultra-flat integrated dispersion is pumped to generate one relatively flat single soliton source spanning over 150 nm. Besides, one extraordinary soliton crystal with single vacancy demonstrates the local relatively flat microcomb lines when the inner soliton spacings are slightly irregular. Our work paves a new way for soliton-based applications owing to the relatively flat spectral characteristics.

Bioaerosols exhibit significant broadband extinction performance and have vital impacts on climate change, optical detection, communication, disease transmission, and the development of optical attenuation materials. Microbial spores and microbial hyphae represent two primary forms of bioaerosol particles. However, a comprehensive investigation and comparison of their optical properties have not been conducted yet. In this paper, the spectra of spores and hyphae were tested, and the absorption peaks, component contents, and protein structural differences were compared. Accurate structural models were established, and the optical attenuation parameters were calculated. Aerosol chamber experiments were conducted to verify the optical attenuation performance of microbial spores and hyphae in the mid-infrared and far-infrared spectral bands. Results demonstrate that selecting spores and hyphae can significantly reduce the average transmittance from 21.2% to 6.4% in the mid-infrared band and from 31.3% to 19.6% in the far-infrared band within three minutes. The conclusions have significant implications for the selection of high-performance microbial optical attenuation materials as well as for the rapid detection of bioaerosol types in research on climate change and the spread of pathogenic aerosols.

A high-quality optical microcavity can enhance optical nonlinear effects by resonant recirculation, which provides a reliable platform for nonlinear optics research. When a soliton microcomb and a probe optical field are coexisting in a micro-resonator, a concomitant microcomb (CMC) induced by cross-phase modulation (XPM) will be formed synchronously. Here, we characterize the CMC comprehensively in a micro-resonator through theory, numerical simulation, and experimental verification. It is found that the CMCs spectra are modulated due to resonant radiation (RR) resulting from the interaction of dispersion and XPM effects. The group velocity dispersion induces symmetric RRs on the CMC, which leads to a symmetric spectral envelope and a dual-peak pulse in frequency and temporal domains, respectively, while the group velocity mismatch breaks the symmetry of RRs and leads to asymmetric spectral and temporal profiles. When the group velocity is linearly varying with frequency, two RR frequencies are hyperbolically distributed about the pump, and the probe light acts as one of the asymptotic lines. Our results enrich the CMC dynamics and guide microcomb design and applications such as spectral extension and dark pulse generation.

铌酸锂晶体光学电场传感器为全介质结构，具有宽带宽、对被测电场干扰小的优点，但其灵敏度较低。因此，分析了晶体几何尺寸对传感器灵敏度的影响机理，得出通过增加沿外加电场方向的晶体尺寸同时减少晶体横截面上沿外加电场垂直方向的晶体尺寸来提高传感器的灵敏度。使用COMSOL仿真分析了铌酸锂晶体不同厚度、宽度、长度对晶体内部电场强度的影响，得出晶体厚度从15 mm减小到3 mm和宽度从3 mm增加到22 mm时，晶体内部电场强度分别提高约5.1倍和12.3倍；晶体长度从15 mm变化到55 mm时，晶体内部的电场强度变化仅约为5%。设计并研制出晶体尺寸分别为3 mm×3 mm×42.2 mm (x×y×z)，3 mm×6 mm×42.2 mm (x×y×z)，6 mm×6 mm×42.2 mm(x×y×z)的三只铌酸锂晶体电场传感器，并搭建工频电场测试平台，测试得出三只电场传感器的灵敏度分别为0.243 mV/(kV·m⁻¹)、0.758 mV/(kV·m⁻¹)、0.150 mV/(kV·m⁻¹)。当晶体厚度和长度一定且晶体宽度从3 mm增加到6 mm时，传感器灵敏度提高3倍。当晶体宽度和长度一定且晶体厚度从6 mm减小到3 mm时，传感器灵敏度提高5倍。结合仿真与实验结果得出：在晶体长度一定时，可以通过设计使用宽度更宽、厚度更薄的晶体，研制出高灵敏度的电场传感器。

荧光显微成像具有高分辨率、高灵敏度、高分子特异性以及非介入性的优点，可以在微米乃至纳米尺度下表征样本的形态学与分子功能学信息，成为了生命科学研究的重要工具。随着微观生物学研究的不断深入，荧光显微成像被期待能够动态且立体地观测微观生物结构与分子事件。文中系统性地梳理了近年来快速三维荧光显微成像技术的研究进展，包括点扫描式成像、宽场成像与投影断层成像在提高成像速度、拓展成像维度以及增强成像质量等方面的主要技术手段、改进策略与代表性研究成果，并展望了快速三维荧光显微成像技术的未来挑战与发展前景。