The liquid crystal spatial light modulator (LC-SLM) is a widely utilized device for optical field modulation. However, it is commonly plagued by the significant zero-order beam in the output diffraction pattern. To address this limitation, we propose a compact LC-SLM coupling module based on the principle of total internal reflection, which effectively eliminates the zero-order beam while preserving high energy efficiency. When incorporated into a holographic display system, the module markedly improves the image quality. When integrated into a holographic optical tweezer system, the module facilitates the generation of a zero-order-free polygonal vortex conveyor, enabling precise manipulation of individual particles and particle ensembles. The experimental results demonstrate the superior performance of the proposed LC-SLM coupling module, providing a robust and versatile platform for applications in holographic optical tweezers, microscopic imaging, and holographic projection.

The integration of array structures with twisted partially coherent beams significantly enhances their potential for complex light field manipulation, particularly in optical communications and optical manipulation. Nevertheless, achieving high-efficiency synthesis and robust steering of twisted light arrays poses a formidable challenge. In this study, we present an experimental scheme for the generation of customized dual-layer twisted light arrays. The experimentally recorded light field profiles display high fidelity with numerical simulations, showing excellent consistency in intensity patterns. Moreover, it is demonstrated that the synergistic interplay between the array structure and twist factors allows for the precise tailoring of the beam field's propagation dynamics. Our findings reveal how essential parameters govern beam evolution, enabling precise control over complex structured fields and promoting versatile applications in optical trapping and optical communication.

Phase-sensitive optical time-domain reflectometry (φ-OTDR)-based distributed optical fiber acoustic sensing systems have been widely applied in large-scale security monitoring due to their excellent spatial resolution, long-distance sensing capability, and immunity to electromagnetic interference. Currently, the recognition of DAS signals primarily relies on convolutional neural networks (CNNs). However, CNNs are susceptible to random noise interference and the diversity of vibration signals in complex environments. As a result, they may capture spurious features that are statistically correlated with the training data but unrelated to the target events. When such correlations fail in the testing environment, recognition accuracy and robustness degrade significantly. To address this problem, this paper proposes an integrated one-dimensional convolutional structure, WTSEConv1d, which integrates WTConv with the Squeeze-and-excitation attention mechanism. WTConv effectively expands the model’s receptive field with low parameter overhead, improving its ability to model long-term dependencies and thus increasing event classification accuracy. Nevertheless, when processing φ-OTDR signals, WTConv may exhibit excessive responses to common high-frequency noise. To address this issue, the proposed WTSEConv1d-Net incorporates the SE attention mechanism into WTConv to dynamically suppress redundant channel activations and guide the model to focus on critical vibration patterns, thereby enhancing feature representation capability. Experimental results show that the proposed method achieves high classification accuracy in recognizing typical vibration events in the public dataset, including 01_background, 02_dig, 03_knock, 04_water, 05_shake, and 06_walk, and exhibits strong capability in focusing on effective signal regions. Furthermore, to evaluate the generalization capability and recognition stability of the model under different application scenarios, an external validation was conducted on a self-collected buried fiber-optic dataset. The results demonstrate that the proposed method still maintains favorable recognition performance under the tested scenarios. These improvements enhance the intelligent sensing performance and engineering applicability of φ-OTDR systems under complex operating conditions.

In the strongly nonlocal regime, controllable propagation of arbitrary partially coherent spatiotemporal wave packets is achieved by constructing general solutions of the (3 + 1)-dimensional nonlinear Schrödinger equation and tailoring the initial pulse. The three-dimensional intensity distribution and multi-parameter control of spatiotemporal cosine-Gaussian dual-layer twisted Laguerre Gaussian Schell-model array wave packets with array phase are further investigated. Results show that the peak intensity exhibits pronounced spatiotemporal correlations; the chirp factor governs temporal shifting and broadening, while the array factor reshapes the transverse energy flow and drives steady-state evolution. This work advances the fundamental research on spatiotemporally twisted array beams in strongly nonlocal nonlinear media.

This study proposes a chiral metamaterial integrated with phase-change materials, achieving a remarkable dynamically tunable chiral response with a resonant frequency stabilized at 1.611 THz. The designed metamaterial utilizes a pi-shaped metal resonator embedded with a vanadium dioxide (VO2) patch to break mirror symmetry and generate strong circular dichroism (CD). Leveraging the reversible insulator-to-metal phase transition of VO2, the chiral response is dynamically controlled, enabling a continuous transition of chirality from -0.699 to +0.719 across a chirality continuum. Compared with existing phase-change chiral metamaterials, our design exhibits a wider CD tuning range. Notably, the resonant frequency remains identical at the two stable phase states (fully insulating and fully metallic) of VO2, which is advantageous for bistable switching applications. These results highlight the significant potential of phase-change-driven metamaterials for advanced applications in tunable chiral sensing, high-precision polarization manipulation, and adaptive photonic devices.

We propose a new twisted partially coherent beam source termed the radial anisotropic twisted Hermite-Gaussian Schell-model beam array (RATHGSMBA). An analytical expression for the cross-spectral density function of the RATHGSMBA is derived, and its propagation characteristics in non-Kolmogorov turbulence are analyzed. We demonstrate that each sub-beam undergoes splitting and rotates uniformly in the same direction during propagation. After a certain distance, beam divergence causes the intensities of adjacent sub-beams to overlap, resulting in complex interference profiles. In the far field, the overall intensity distribution converges to that of an individual array element due to the progressive dispersion of the sub-beams. Multiple adjustable parameters provide control over the beam profile evolution throughout propagation. This work proposes what we believe to be a new class of customizable partially coherent sources and suggests potential applications leveraging the twist phase in areas such as high-power laser systems, optical communications, and manipulation.

Recent advancements in deep learning have improved the signal recognition capabilities of distributed fiber-optic vibration sensors. However, most existing research focuses on closed-set scenarios, assuming that all potential events are known and accounted for during training. In practical applications, the environmental complexity surrounding sensing fibers makes it impractical to anticipate and train on every intrusion event. To address this, we propose a novel Hierarchical Attention Network with Openmax (HANO) model that integrates a hierarchical attention mechanism with the Openmax algorithm. This model effectively extracts and emphasizes discriminative features at multiple levels, enhancing the recognition of both known and unknown events. Incorporating the Openmax layer enhances the classifier’s ability to manage unknown classes, thereby facilitating open-set recognition. To validate the effectiveness of the HANO model, we conducted experiments involving human intrusion events within a fenced area. The network parameters were optimized accordingly, and HANO’s performance was compared against the Swin Transformer, as well as models utilizing Softmax and Sigmoid layers. Additionally, we benchmarked it against other open-set recognition algorithms. The experimental results demonstrate that the HANO model achieves an overall recognition accuracy exceeding 95%, outperforming the comparative methods. These results demonstrate that the HANO model enhances the recognition of open-set events, indicating its strong potential for practical applications, particularly in scenarios requiring precise intrusion detection, such as security monitoring and vibration detection.

We propose a partially coherent twisted off-axis double vortex (PCTODV) beam and investigate its propagation characteristics in atmospheric turbulence. By employing the extended Huygens–Fresnel principle and the Wigner distribution function, we derive the corresponding analytical expressions and perform numerical simulations to validate our findings. The findings reveal that PCTODV beams possess a wider array of tunable parameters than single vortex beams with central phase singularities, which is beneficial for atmospheric turbulence propagation. The twist factor size notably affects the beam evolution rate in turbulence, with an optimized twist factor enhancing resistance to turbulence. Moreover, factors such as increased wavelength, larger initial beam waist, greater inner turbulence scale, higher refractive index structure constant, and reduced M2 factor contribute to improved transmission stability. These insights advance the understanding of vortex beam propagation in turbulent atmospheric optical communication systems.

We conduct numerical simulations of the transmission of controllable cross-phase beams in strongly nonlocal nonlinear media (SNNM), investigate the underlying physical mechanisms of mode conversion in various beam structures, and analyze the impact of cross-phase on the transmission characteristics of multibeam coupling. It is observed that nonuniformity in energy distribution during single-beam transmission drives the redistribution of transverse energy, resulting in the dynamic conversion of the beam mode. This beam mode conversion process exhibits notable stability. The initial configuration of the beam array is determined by the off-axis parameters of each constituent beam element. By adjusting the cross-phase and chirp parameters, the same array can exhibit a variety of periodic propagation behaviors. The evolution of orbital angular momentum (OAM) density is periodic, with its spatial distribution exhibiting axial symmetry. The results presented in this paper provide theoretical insights into the fields of optical communication and particle manipulation.

This paper proposes a controllable anomalous elliptical hollow cross-phase (CAEHCP) beam. Based on the Huygens-Fresnel integral principle and the transformation matrix of strong nonlocal nonlinear medium (SNNM), the analytical expression of beam propagation in SNNM is derived. The propagation characteristics of the CAEHCP beam-including intensity, phase, axial intensity, curvature radius, and beam width-are computed and analyzed numerically. Additionally, we examine the impact of the cross-phase on critical power variations. The results indicate that, under certain conditions, the intensity distribution demonstrates symmetry relative to parameter a, enabling the CAEHCP beam to transition into a hollow structure. The cross-phase effect induces periodic changes and rotation in the transverse intensity distribution of the CAEHCP beam. When the beam modulation parameter is a complex number, the intensity distribution exhibits rotational characteristics, with the rotation amplitude gradually increasing as the cross-phase increases. These findings establish a theoretical foundation for potential applications of cross-phase beams in optical communication, light-field control, and related fields.

In unstable environments, such as atmospheric turbulence, designing light field structures and phase distributions is crucial for mitigating beam quality degradation. This study constructs an array of superposed twisted Gaussian Schell-model beams with array phases, enabling the beam to self-split and self-stabilize. The array phase not only alters the beam's spectral density distribution but also significantly affects the evolution of its coherence. Under far-field conditions, it enables the beam to split into an array of fields, with the normalized orbital angular momentum flux density reflecting the field distribution and maintaining stability during propagation. This design effectively mitigates the effects of beam spreading and quality degradation caused by turbulence, providing a theoretical basis for high-stability, high-quality light field propagation in complex environments.

Existing deep learning models often underperform in cross-domain few-shot tasks for distributed vibration sensing (DVS), largely due to domain shifts introduced by variations in device types and deployment scenarios. To address this challenge, we introduce the cross-domain few-shot learning (CDFSL) paradigm to the field of distributed fiber-optic vibration signal recognition for the first time and propose a novel framework, the cosine-initialized masked autoencoder (Cosine-Initialized-MAE). This approach begins with self-supervised pretraining on large-scale unlabeled source-domain data using a masked autoencoder (MAE), enabling the extraction of transferable, general-purpose feature representations. Subsequently, the model is efficiently adapted to the target domain using only a few labeled samples, via a single-step fine-tuning procedure that incorporates weight imprinting and cosine similarity classification. Departing from conventional episodic evaluation, our method employs a fixed evaluation protocol: the model is fine-tuned once on a k-shot support set (k is an element of {1, 5, 10}) and then evaluated on the remaining (500-k) samples per class. The proposed framework achieves accuracies of 78.92%, 87.84%, and 91.80% on 5-way 1-shot, 5-shot, and 10-shot tasks, respectively-substantially outperforming established self-supervised and few-shot learning baselines. These results highlight the framework's strong generalization under limited supervision and underscore its potential for low-resource cross-domain recognition in DVS systems.

Distributed optical fiber vibration sensing systems (DVS) are widely employed in perimeter security for their high sensitivity, simplicity, and strong immunity to electromagnetic interference. However, these systems are facing with two serious challenges: accurately classifying closed-set signals (known events) and detecting open-set signals (unknown events). To address this, we propose an open-set recognition framework, ResEff-OpenGAN-LN. By integrating layer normalization into the OpenGAN architecture, this framework mitigates instability caused by input feature variations while leveraging ResEff for efficient feature extraction to enhance closed-set classification. Experimental results show that ResEff achieves 99.92% accuracy on closed-set tasks, and ResEff-OpenGAN-LN obtains an AUROC of 0.9900 with 96.63% overall accuracy on mixed datasets containing open-set and closed-set signals, validating its potential to improve intrusion detection and reduce false alarms.

Researchers have extensively investigated beam propagation theory in strongly nonlocal nonlinear media (SNNM), and they have validated and applied the corresponding ABCD matrix theory. In this study, we propose modified ABCD matrix parameters that rigorously satisfy optical propagation theory, enabling effective coupling with complex optical systems. Based on this theoretical model, we numerically simulate and systematically investigate the propagation dynamics of dual-layer twisted array beams. In the propagation dimension, we reveal a state-switching mechanism among “self-focusing, self-stabilization, and self-divergence” governed by critical parameters, and discover an SNNM-free space interface-induced beam rotation reversal phenomenon. By precisely tuning the off-axis parameters of individual solitons, one can actively design the array's structural configuration. Numerical simulations further demonstrate characteristic dynamic behaviors of dual-layer twisted array breathing solitons. These findings are expected to provide a theoretical foundation for the functional applications of SNNM and dual-layer twisted array beams.

This paper introduces a new controllable anomalous hollow cosh-Gaussian beam (CAHcGB). Based on the Snyder-Michell model and the ABCD matrix description of strongly nonlocal nonlinear media (SNNM), we investigate the transmission characteristics of CAHcGB. Analytical expressions for the electric field, beam width, wavefront curvature radius, and critical power of CAHcGB in SNNM are derived. The results demonstrate that CAHcGB undergoes periodic evolution during transmission in SNNM, influenced by both the beam parameters and the initial beam power. When the critical power equals the incident power, the beam width remains unchanged throughout transmission, resembling a CAHcGB soliton; otherwise, it periodically changes, akin to a breather. The study also reveals that the on-axis intensity evolution curve can exhibit various shapes such as concave, platform, or Gaussian-like, depending on the input power. The research results hold significant potential for applications in optical fiber communication systems, all-optical networks, and optical switches.

Based on the integral superposition method of constructing partially coherent beam model, a partially coherent crescent-like multi-vortex-correlated Schell-mode beam is first proposed. Numerical simulation results show that the beam possesses a crescent-like intensity distribution with multiple off-axis vortices on the source plane. By means of digital holography, the spatial light modulator was loaded with holograms, which realized experimentally the generation of this beam. The experimental normalized intensity distribution is basically consistent with the theoretical results. Adjusting the parameter N0, off-axis distance s and phase angle & phi;0, one can precisely control the number and position of multiple off-axis vortices. The results obtained are of importance for adjusting the beam centroid and studying vortex optics.

We believe this to be a new superposition twisted Hermite-Gaussian Schell-model (STHGSM) beam hat is proposed. Analytic formulas for the intensity distribution and propagation factor of the STHGSM beam in non-Kolmogorov turbulence are derived by utilizing the generalized Huygens-Fresnel principle (HFP) and the Wigner function. The evolution characteristics of STHGSM beams propagating are numerically calculated and analyzed. Our findings indicate that the light intensity of the STHGSM beam gradually undergoes splitting and rotation around the axis during propagation through non-Kolmogorov turbulence, eventually evolving into a diagonal lobe shape at a certain distance of transmission. The anti-turbulence capability of the beam strengthens with higher beam order or twist factor values.