Composites have added new dimensions to the design and construction of buildings and structures. One of the wider spread composite applications in the construction industry is composite beams or pillars, which can be manufactured through pultrusion processes. These types of construction elements are usually used to withstand the weight of large loads, so their integrity must be guaranteed. Due to optical sensors’ advantages over their electrical counterparts—small sizes, low weight, non-conductive, and immunity to electromagnetic interference—and FBGs having an outstanding position among optical fibre sensors—due to their multiplexation capability and relatively easy monitoring—in this study, we propose the integration of FBG sensors for the observation and analysis of the integrity of structures made with composite beams over time. The validation test results showed the successful embedding integration of FBG-based fibre optical sensors in an FRP pultrusion beam and strain transmission up to 7500 µɛ from the composite test piece to the sensor. Additionally, we were able to anticipate the piece failure by the FBG spectrum deformation.

We propose and experimentally demonstrate a reconfigurable two-dimensional (2D) photonic beamformer architecture based on a dispersion-diversity heterogeneous multicore fiber (MCF) and fiber Bragg grating (FBG) arrays. The system employs two independent true-time-delay-line (TTDL) stages that enable 2D beamforming using a single tunable laser source. Continuous and discrete control of the azimuth and elevation angles, respectively, is achieved by combining wavelength-dependent beam-pointing angle periodicity with the dispersion diversity of the heterogeneous MCF. The distributed beamformer concept is validated for a 5 × 5 equivalent phased antenna array using 5-km heterogeneous MCF and an FBG array composed of seven gratings inscribed in each of five single-mode fibers. Each FBG was inscribed using a femtosecond laser at a specific longitudinal location and centered at a distinct wavelength within the 1530–1573 nm range. As a proof of concept, the system demonstrates continuous azimuthal steering over 90° and seven discrete elevation angles from −45° to +45°. Measurements of differential group delay and phase difference across all outputs show an average time-delay error below 0.5 ps with a maximum standard deviation of 1.03 ps, corresponding to a beam-pointing error under 2°. The retrieved array-factor patterns closely match theoretical predictions, confirming precise control in both azimuth and elevation. Overall, this work presents a compact, energy-efficient, and reconfigurable photonic architecture for 2D beamforming, offering a scalable, fiber-distributed solution for next-generation, beyond-5G, and 6G communication systems.

An elastomeric optical fiber core was fabricated by drawing a 1160-D thermoplastic polyurethane preform. The cut-back technique was used to measure fiber attenuation for a light spectrum ranging from 550 nm to 875 nm, resulting in an average value of less than 0.25 dB/cm, which is suitable for use in short-distance applications. The potential of the fiber was evaluated in two applications where the advantages of this type of optical fiber, its elasticity and flexibility, are important. In the first application, for weight measurement, the sensor response showed asymptotic behavior at high weights that can be divided into two linear sections of 2.9 dB/N for weights ranging from 0 N up to 1 N, and 2.1 dB/N for 1 N to 1.7 N. In the second application, as a vibration sensor, signals were detected between 1 kHz and 20 kHz with an amplitude of approximately 35 dB above the background noise.

Implementation of the Hilbert Transform (HT) for temperature monitoring using an interferometric fiber sensor is presented. The method’s effectiveness is confirmed through modeling, simulation, and experimental results. This approach simplifies the process of monitoring the phase of an interferometric signal from a fiber sensor. Using a Fabry-Perot interferometer as the sensing element, it is demonstrated that the HT method enables accurate temperature measurement. The results show a high sensitivity and precision, with an error margin of less than 0.1°C, demonstrating the method’s reliability and potential for various applications.

We embedded optical sensors based on fiber Bragg gratings between each layer of a multidirectional carbon fiber reinforced polymer for monitoring temperature and strain distribution over curing process using both, thermal and microwave heating method.

During recent years, the optical-fiber-based simultaneous sensing of strain and temperature has attracted increased interest for different applications, e.g., in medicine, architecture, and aerospace. Specialized fiber layouts further enlarge the field of applications at much lower costs and with easier handling. Today, the performance of many sensors fabricated from conventional fibers suffers from cross-sensitivity (temperature and strain) and relatively high interrogation costs. In contrast, customized fiber architectures would make it possible to circumvent such sensor drawbacks. Here, we report on the development of a high-quality coupled-core fiber and its performance for sensors—from the initial fiber layout via elaboration of the preform and fiber up to the sensor evaluation. A compact, high-speed, and cost-effective interrogation unit using such a specialized coupled-core fiber has been designed to monitor reflectivity changes while even being able to distinguish the direction of the force or impact. Several fiber core material techniques and approaches were investigated, which made it possible to obtain a sufficient volume of material for the required fiber core number and a specialized fiber core geometry in terms of core distances and radial refractive index profile, whilst handling the non-symmetrical fiber architectures of such modeled, complex structures and balancing resources and efforts.