Automatic mode-locking techniques, the integration of intelligent technologies with nonlinear optics offers the promise of on-demand intelligent control, potentially overcoming the inherent limitations of traditional ultrafast pulse generation that have predominantly suffered from the instability and suboptimality of open-loop manual tuning. The advancements in intelligent algorithm-driven automatic mode-locking techniques primarily are explored in this review, which also revisits the fundamental principles of nonlinear optical absorption, and examines the evolution and categorization of conventional mode-locking techniques. The convergence of ultrafast pulse nonlinear interactions with intelligent technologies has intricately expanded the scope of ultrafast photonics, unveiling considerable potential for innovation and catalyzing new waves of research breakthroughs in ultrafast photonics and nonlinear optics characters.

Surface-Enhanced Raman Scattering (SERS) integrated with optical waveguide sensing offers a transformative approach to overcoming the limitations of conventional SERS techniques, such as complex alignment requirements and limited signal collection efficiency. By leveraging the unique properties of optical waveguides, this integration significantly enhances detection sensitivity, simplifies sensor design, and enables the analysis of ultra-low concentration analytes in trace-volume samples. This review explores the latest advancements in combining diverse optical waveguide architectures with SERS technology, focusing on strategies to optimize the sensing interface and SERS substrate design for maximal Raman signal enhancement. By enabling efficient analyte excitation and enhanced scattered signal collection through waveguide-mediated light-matter interactions, this approach unlocks new possibilities for high-sensitivity Raman detection. Furthermore, we discuss the potential of this integration to drive breakthroughs in fields such as biomedical diagnostics, environmental monitoring, and chemical sensing, paving the way for next-generation, portable and ultra-sensitive sensing platforms.

Parallel phase-shifting digital holography (PPSDH) employing a polarization image sensor can suppress zero-order and twin-image noise through a single exposure, achieve instantaneous measurement of complex-valued dynamic objects, and have broad applications in the areas of biomedicine, etc. To improve the imaging resolution of PPSDH, we propose an oversampled super-pixel image reconstruction method, which can be expressed as the implementation of nearest-neighbor interpolation to replace blank pixels in sparse sub-phase-shift holograms. We found experimentally that the maximum spatial lateral resolution of the reconstructed image based on the existing super-pixel method, B-spline, bicubic, bilinear, and the proposed nearest-neighbor interpolation was 12.4 µm, 11.4 µm, 9.8 µm, 8.8 µm, and 7.8 µm, respectively. The main reason for not reaching the ideal value of 6.9 µm was the inherent residual zero-order and twin-image noise, which needs to be removed in the future.

Attitude sensors are critical elements in the field of automation control. In this study, we propose and demonstrate a whisker-inspired fiber attitude sensor (WI-FAS) capable of simultaneously measuring pitching and rolling angles. A photopolymerized whisker grows out of the central core of a seven-core fiber (SCF) and holds a solid pendulum. Six parallel Fabry-Perot interferometers formed between the SCF. The pendulum transforms variations in cavity length caused by pitching and rolling into the evolution of the interference signal. A fan-in/fan-out device is used to implement space division multiplexing of the SCF, enabling the proposed sensor to judge direction. We also develop a mathematical expression to explain the association between the pitching and rolling angles and the WI-FAS output signals. Mechanical simulations are carried out to investigate the primary factors that affect the sensitivity. With optimum settings, the proposed WI-FAS achieves continuous and simultaneous monitoring of pitching and rolling with a sensitivity of greater than 0.13 nm/ $^\circ$ in the angle range of $-180 ^\circ$ to $+180 ^\circ$ . The suggested WI-FAS exhibits the advantages of compact size, high sensitivity, and has the ability to monitor pitching and rolling simultaneously. Thus it is a competitive candidate in the field of attitude sensing.

As a strong interference source for the all-time optical imaging surveillance of maritime targets, sea surface glare is difficult to mitigate accurately because of its time-varying characteristics due to lighting conditions and seawater fluctuations. In this paper, we propose an adaptive suppression approach to sea surface glare, which establishes a geographic polarization suppression model based on real-time information regarding geographic positioning and the orientation information of the floating platform, and also combines dynamic polarization control and pixel normalization to achieve adaptive suppression of sea surface glare. Experimental results show that this approach can mitigate the influence of rapidly changing glare effectively, and the SSIM indexes between the images without glare and those with glare suppression of the same scenes exceed 0.8, which is suitable for all-time glare suppression on the sea surface under natural lighting conditions.