Current Issue : April-June Volume : 2026 Issue Number : 2 Articles : 5 Articles
This study investigates the influence of optical loss induced by the macro-bending of optical fibers on the signal quality of an optical frequency-domain reflectometry (OFDR) system. First, the finite element software COMSOL 5.3 was used to perform numerical simulations of the optical loss of single-mode fibers under different bending radii. The simulations revealed that when the bending radius is relatively small, the optical loss exhibits oscillation as the bending radius varies. Next, an optical backscatter reflectometer (OBR) was employed to measure the optical loss of the optical fiber under different bending radii and numbers of bending loops. The experimental results showed good consistency with the simulation results, and the variation law of optical loss under different bending radii and numbers of bending loops was clarified. An OFDR strain demodulator was used to demodulate the strain signals under loaded conditions with different fiber bending radii and numbers of bending loops. It was found that when the cumulative optical loss increases to a certain threshold, the demodulated signal quality degrades significantly—this confirms that macro-bending loss directly impacts the SNR of OFDR output signals. The findings of this study provide practical guidance for the bending-oriented deployment of optical fiber sensors, which was successfully validated through a real-world structural strain monitoring case....
LiDAR technology has undergone significant advancement in recent years, establishing itself as a technique for long-range, high-precision detection. As its use expands into more intricate scenarios, the need to overcome blind spots in the scanning field and enhance system stability has become increasingly critical. This paper introduces a novel coaxial LiDAR system featuring a double-clad optical fiber-based receiver which consists of a single-mode fiber core for the emission of the laser beam and a multimode inner cladding for the collection and transmission of the back-reflected beam. The real-time system is specifically engineered to measure distances in both near and far fields, eliminating blind spots. Experimental evaluations demonstrate that our system achieves a detection range of 0.2–70.7 m, with a distance accuracy of 3.4 cm and an angular resolution of 0.018◦. Compared with conventional LiDAR systems, our approach eliminates the need for complex optical pathway designs and algorithmic compensation. It offers a simplified structure, enhanced stability, and high accuracy....
To address the low accuracy in electric field calculation for complex three-dimensional transmission lines and the multi-objective cooperative optimization of cable hanging points, an improved fusion model is proposed. This model integrates an enhanced sparrow search algorithm with the charge simulation method to optimize the position and magnitude of simulation charges through a dynamic chaotic mapping mechanism and a nonuniform segmented charge strategy. These improvements mitigate the high-curvature boundary errors associated with empirical charge setting in traditional methods. Experimental results demonstrated that after 500 iterations, the proposed algorithm achieved an average potential error of only 0.15225% at checkpoints, with most errors remaining below 0.5% and terminal errors not exceeding 3%. For multi-objective suspension point selection, a weighted comprehensive scoring method is used instead of traditional Pareto optimization or fuzzy membership functions to integrate constraints such as electric field strength, mechanical stability, leakage current, and anti-interference ability. This method offers superior engineering practicality and computational efficiency for decision-making under multiple constraints. The candidate hanging point M exhibits an electric field strength of 15.2 kV/m and a leakage current of 0.8 mA, which met safety standards and improved overall performance by 37.6%. The proposed model provides reliable technical support for smart grid transmission line planning and optical cable deployment, with potential applications in multi-physical field coupling and ultra-high-voltage direct current scenarios....
To meet the increasing demands for data, elastic optical networks (EONs) require highly efficient resource management. While classical Routing and Spectrum Assignment (RSA) algorithms establish a path and allocate spectrum, advanced versions such as Routing, Modulation-format-selection, and Spectrum Assignment (RMSA) also optimize modulation format selection. However, these approaches often lack adaptability to diverse network aspects. The hybrid routing and spectrum assignment (HRSA) algorithm offers a more flexible and robust approach by providing multiple choices between route (resource savings) and spectrum prioritization (fragmentation mitigation and network load balancing) for each network node pair. Despite its potential, the adaptive nature of HRSA introduces complexity, and the influence of topological features on its decisions remains not fully understood. This knowledge gap hinders the ability to optimize network design and resource allocation fully. This paper examines how topological features influence HRSA’s adaptive decisions regarding routing and spectrum assignment prioritization for sourcedestination node pairs in EONs. By employing machine learning approaches—Decision Tree (DT), Random Forest (RF), Extreme Gradient Boosting (XGBoost), and Support Vector Machine (SVM)—we model and identify the key topological features that influence HRSA’s decision-making. Then, we compare the models generated by each approach and extract insights using an a posteriori analysis technique to evaluate feature importance. Our results show the algorithm’s behavior is highly predictable (over 91% accuracy), with decisions driven primarily by the network’s structure and node metrics. This work advances the understanding of how topological features influence the RSA problem....
Exploding or concentrating beams, vortex beams, and cylindrical vector beams have a precisely shaped transversal amplitude profile such that they produce a continuously concentrating and intensifying focal spot upon focusing as the lens aperture is opened. This effect is the physical manifestation of the mathematical fact that Fresnel diffraction integral predicts an infinite intensity at the focus when the aperture effects are ignored. Here, using a full electromagnetic, nonparaxial focusing model, we show that the singularity in exploding cylindrical vector beams is an artifact of the paraxial approximation. Nevertheless, the exploding or concentrating effect, alien to any other light beam with finite power, keeps going up to unit numerical aperture, equivalent to infinite aperture radius. This unique feature enables a dynamic control of the focal intensity and spot size down to the subwavelength scale using a single light beam, imitating similar control when focusing an ideal plane wave, but requiring a finite amount of power....
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