介电常数近零材料及相关物理现象近年来逐渐成为一个快速发展的研究领域。在介电常数近零材料中，光与物质相互作用显著增强，为设计新型光学功能器件提供了重要思路。从线性和非线性光学范畴综述了介电常数近零材料中光与物质相互作用的原理与应用进展。在线性光学部分，讨论了透明导电氧化物材料的光学性质、介电常数近零模式、载流子的电调控等方面的内容。在非线性光学部分，讨论了介电常数近零材料在非线性折射率调控、非线性频率转换以及时变ENZ材料中的非线性光学响应等方面的研究进展。最后，展望了介电常数近零材料领域的未来研究方向和应用领域。

针对电润湿电子纸存在油墨回流、接触角迟滞、电荷捕获等现象导致图像对比度不高、纹理边缘不清晰和细节丢失等问题，本文提出了一种基于图像分割和动态直方图均衡的电润湿显示器图像增强算法。该算法综合了最大类间方差法（Otsu法）和最大熵分割算法的优点，提出了基于方差权重的最大类间方差和最大熵阈值分割算法。利用该分割算法把图像分割为背景区和目标区，将两个区域的亮度均值以及基于方差权重选取的阈值作为分割点将原始图像直方图分成四个子直方图，然后分别对子直方图进行灰度重分配，最后对四个子直方图进行直方图均衡。实验结果表明：与其他将直方图进行分区的直方图均衡算法相比，该算法图像质量评价指标峰值信噪比提高约25.6%~45.5%，熵差降低约29.1%，结构相似度更接近1。同时将其应用在电润湿显示器上，其显示图像具有更高的对比度，细节纹理更加清晰，具有更好的视觉效果。

Cylindrical vector beams and vortex beams, two types of typical singular optical beams characterized by axially symmetric polarization and helical phase front, possess the unique focusing property and the ability of carrying orbital angular momentum. We discuss the formation mechanisms of such singular beams in few-mode fibers under the vortex basis and show recent advances in generating techniques that are mainly based on long-period fiber gratings, mode-selective couplers, offset-spliced fibers, and tapered fibers. The performances of cylindrical vector beams and vortex beams generated in fibers and fiber lasers are summarized and compared to give a comprehensive understanding of singular beams and to promote their practical applications.

Goodness of fit is demonstrated for theoretical calculation of z-scan data based on beams propagating in the nonlinear medium and the Fresnel–Kirchhoff diffraction integral in experiments with high nonlinear refraction and absorption. The constancy of nonlinear optical parameters is achieved regardless of sample thickness and laser intensity, which clarifies the physical significance of optical parameters. We have obtained γ = 2.0 × 10^?19 m²/W and β = 5.0 × 10^?13 m/W for carbon disulfide excited by a pulsed laser at 800 nm with pulse duration of 35 fs, which are independent of sample thickness and laser intensity. Affirming constancy of the extracted parameters to the incident light intensity may become a practice to verify the goodness of the z-scan experiment.

A polarization-insensitive plasmonic absorber is designed consisting of Au fishnet structures on a TiO₂ spacer/Ag mirror. The fishnet structures excite localized surface plasmon and generate hot electrons from the absorbed photons, while the TiO₂ layer induces Fabry–Perot resonance, and the Ag mirror acts as a back reflector. Through optimizing the TiO₂ layer thickness, numerical simulation shows that 97% of the incident light is absorbed in the Au layer. The maximum responsivity and external quantum efficiency of the device can approach 5 mA/W and ～1%, respectively, at the wavelength of 700 nm.

Surface-enhanced Raman spectroscopy (SERS) with high-sensitivity performance is a very necessary detection technology. Here, we present a method for increasing the performance of SERS based on silver triangular nanoprism arrays (ATNAs) vertically excited via a focused azimuthal vector beam (AVB). The ATNA substrates with different structural parameters are prepared based on the traditional self-assembled and modified film lift-off technique. Based on a theoretical model established adopting the structural parameters of the ATNA substrates, theoretical simulation results show that AVB excitation can achieve greater electric-field enhancement than linearly polarized beam (LPB) excitation. Experimental result indicates that SERS sensitivity obtained via AVB excitation is 10 13M (1 M = 1 mol/L) using rhodamine 6G (R6G) as the target analyte, which is 2 orders of magnitude lower than that of LPB excitation (10 11M). Meanwhile, the uniformity and reproducibility of the ATNA substrates are examined using Raman mapping and batch-to-batch measurement, respectively, and the Raman enhancement factor is calculated to be ～3.3×107. This method of vector light field excitation may be used to improve the SERS performance of the substrates in fields of ultra-sensitive Raman detection.

The synergy of a plasmonic tip and fiber-based structure light field excitation can provide a powerful tool for Raman examination. Here, we present a method of Raman spectrum enhancement with an Ag-nanoparticles (Ag-NPs)-coated fiber probe internally excited via an azimuthal vector beam (AVB), which is directly generated in a few-mode fiber by using an acoustically induced fiber grating. Theoretical analysis shows that gap mode can be effectively generated on the surface of the Ag-NPs-coated fiber probe excited via an AVB. The experimental result shows that the intensity of Raman signal obtained with analyte molecules of malachite green by exciting the Ag-NPs-coated fiber probe via an AVB is approximately eight times as strong as that via the linear polarization beam (LPB), and the activity of the AVB-excited fiber probe can reach 10 11 mol/L, which cannot be achieved by LPB excitation. Moreover, the time stability and reliability are also examined, respectively.