Current Issue : October-December Volume : 2025 Issue Number : 4 Articles : 5 Articles
Optical–chemical sensors based on optical fibers can be made in reflection or transmission schemes. In the reflection scheme, the sensing area is typically present at the end of the fiber, and the light source and the detector are placed on the same side of the fiber. This approach can be exploited to achieve chemical probes useful in several application fields where remote sensing is required. In this work, to obtain an extrinsic optical fiber chemical sensor in a reflection scheme, two optical fibers are used to monitor a chemically sensitive region achieved by a C-shaped waveguide with a molecularly imprinted polymer (MIP) as a core between the optical fibers. The proposed micrometer-sized probe is developed and tested as a proof of concept via a MIP for 2-Furaldehyde (2-FAL) detection of interest in food and industrial applications. The experimental results of the proposed sensing approach showed several advantages, such as a nanomolar detection limit and an ultra-wide concentration detection range due to different kinds of MIP recognition sites in the optical path between the fibers....
One promising method to increase the bit-rate capacity of optical fibers is the use of Multi-Core Fibers (MCFs). However, the close proximity of the cores can lead to data interference due to crosstalk between them. A novel approach is proposed to suppress crosstalk in MCFs. It is demonstrated that if the refractive index of the cores is weakly modulated harmonically, with each core having a different phase, crosstalk in two-core and three-core fibers can be entirely eliminated. Furthermore, by using specific configurations— either by selecting the fiber length or by arranging the cores’ spatial layout—crosstalk can be suppressed even in fibers with more than three cores....
Flash LiDAR can be used to capture the depth information or contour profile of a target area in one shot and, therefore, has become an important feature in depth sensing devices. Current flash LiDAR devices still suffer from resolution issues due to difficulties in reducing the pixel size of the array sensor. In this paper, a solution has been proposed to resolve this resolution issue by introducing multi-view imaging optics into the flash LiDAR device. Together with scanning illumination over the target area and range image tiling, a fourfold increase in spatial resolution has been achieved, and the working concept can be further extended for resolution enhancement via array expansion. A calibration procedure and shielding mechanism have also been developed to compensate for the issues of crosstalk and stray light, ensuring the quality of the tiled range image. The prototype and corresponding experiment have demonstrated the feasibility of the proposed architecture as an optical solution for enhancing the resolution of flash LiDAR....
Fiber eavesdropping severely endangers the confidentiality of data transmitted in optical networks. Therefore, it is necessary to explore how to detect and locate fiber eavesdropping in an effective approach. To leverage the advantages of the state of polarization (SOP) in detecting various abnormal events while addressing its challenges in acquiring the SOP of different fiber links, we propose a multi-channel joint SOP estimation scheme to estimate the SOP of different fiber spans. Based on the proposed scheme, we provide a comprehensive solution for fiber eavesdropping location and detection in optical communication systems. In this solution, the estimated SOP and optical performance monitoring (OPM) data are utilized for rapid fiber eavesdropping detection and coarse location at the span level. The effectiveness of the solution is validated by experiments. In the aspect of detection, we achieve the detection of the start or end of fiber eavesdropping, the overlapping of fiber eavesdropping and abnormal events, and other abnormal events. The overall accuracy is 99.77%. In the aspect of location, we can locate the fiber span that has been eavesdropped....
Lab-on-fiber technology is deemed pivotal in many fields due to the advantages offered by the mature optical fiber technology. Therefore, the development of optical components integrated into optical fibers is crucial. The ability to integrate metasurfaces into optical fibers has led to a greater number of degrees of freedom that might be used to realize all-in-fiber optical components. Here we explore the potential of plasmonic MSs based on a partial coverage of the phase range, introduced by Hail, but so far essentially unexplored. Exploiting this paradigm, we realize a beam splitter and a focusing lens at the tip of a single mode fiber operating in the near infrared. We show that partial-phase MSs, unlike their standard plasmonic counterparts, enable the generation of two beams, the ordinary and the anomalous one, that have the same polarization state and delivered power, allowing efficiencies of up to ∼30% to be achieved. Furthermore, we demonstrate that it is possible to focus light a few micrometers from the tip without the need of a beam expander. The realized meta-lens has a numerical aperture of 0.71 and a focusing efficiency of 20%, the highest efficiency achieved so far with a flat lens on a fiber tip....
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