Abstract
Abstract Inductively coupled plasma-mass spectrometry analysis was conducted to examine the geochemical composition of K-feldspars from various aplite-pegmatites in the Barroso-Alvão field, focusing on the differences between Li-rich and Li-barren aplite-pegmatites. The study revealed significant variations in the concentrations of minor and trace elements (Rb, Tl, Li, Ga, Pb, Cs, Ba, Be, Ta, and Sn) present in the K-feldspars of Li-barren, spodumene-rich, and petalite-rich aplite-pegmatites. The data also indicate a geographical trend in both mineralogy and geochemistry across the aplite-pegmatites of the Barroso-Alvão field. Li-barren aplite-pegmatites are more concentrated in the southeast, spodumene-rich dominate the center, and petalite-rich varieties are more common in the northwest. Additionally, portable X-ray fluorescence analysis was performed on the crystals of the same samples to evaluate the feasibility of in situ geochemical analysis of K-feldspars, aiming to determine whether an aplite-pegmatite can be quickly identified as Li-rich. This approach seeks to provide a rapid field assessment of whether an aplite-pegmatite justifies further exploration for Li mining. Notably, the trace amounts of Li, Sn, P, and Ta found in K-feldspars are likely due to mineral inclusions of spodumene, cassiterite, apatite, and columbite–tantalite minerals, as observed petrographically in one of these Li-rich aplite-pegmatites.

Abstract
Heritage preservation requires innovative sensing technologies to analyze their chemical composition while minimizing damage. This study introduces a Laser-induced Breakdown Spectroscopy (LIBS) system featuring a fiber laser source and optical fiber-based collection system for the analysis of heritage ceramics. Comparative experiments with a conventional Nd:YAG laser LIBS system highlight the advantages and trade-offs of the fiber laser system in terms of ablation capability, spectral mapping, and depth profiling. Results were validated against X-ray Fluorescence (XRF). Experiments demonstrate minimal surface alteration and high-quality spectral data for elements such as Pb, Fe, Zn, Sb, Mn, Ti Na, Ba and Ca. The compact design and good results position this system as a transformative tool for heritage conservation.

Abstract
Solid-state batteries are prominent in today's research landscape due to their advantages in capacity and safety. This work explores anode-less all-solid-state batteries, a configuration with industrial benefits as it avoids handling alkali metal anodes, albeit with room for improvement. To elucidate the intricacies of these batteries, Laser-Induced Breakdown Spectroscopy (LIBS) served as a pivotal analytical tool, primarily focusing on the negative current collector surface where Li+ nucleation occurs from the Li-rich electrolyte. The use of a fiber-laser for breakdown spectroscopy offers advantages over conventional lasers by producing high beam quality, enabling minimal spot size, and ensuring excellent spatial resolution. LIBS is an asset to verify Li presence, discerning its source, assessing nucleation and distinguishing it from electrolyte-derived Li. For instance, in this work utilizing Li2.99Ba0.005ClO as the electrolyte, LIBS is crucial to elucidate the relationship between Li and other elements like Cl, Zn, or Fe, shedding light on key battery performance aspects. LIBS demonstrated a high potential for verifying in situ Li metal nucleation in anode-less cells. This study highlights its effectiveness in conceptual and product development and advanced quality testing. The application of a clustering method enhanced result interpretability and the distinction between electrolyte and in situ anode regions.

Abstract
In this study, we demonstrate the measurement of electric power using an optical ground wire ( OPGW). The tests were conducted on an OPGW cable from a high-voltage transmission line in Sines, Portugal, operating at 400 kV. A buried fiber position, free of 50 Hz and 100 Hz frequency interference, was selected to confirm that the 50 Hz frequency is not due to mechanical perturbation or electronic noise. Additionally, two suspended fiber positions (at 2500 m and 8500 m), where these frequencies were clearly observed, were analyzed. This study also examined the positioning of poles and splice detection between cables.

Abstract
Polarization-based fiber sensors rely on the dynamics of the Stokes vector at the output of the optical fiber to probe stimuli that induce polarization variations. However, these sensors often suffer from limitations in sensitivity, precision, and reproducibility. In this work, we address these challenges by incorporating concepts from the Mueller matrix formalism to enhance the capabilities of such sensors. Specifically, we measure the Mueller matrix in the polarization basis that describes how the polarization evolves inside the optical fiber. Leveraging this formalism, we configure the system as a precise sensor to detect deformations along the fiber. By utilizing the Fisher Information framework, we significantly improve accuracy and resolution, enabling the detection of subtle perturbations with greater precision. This study introduces a novel approach for precise polarization control and advanced fiber-based sensing applications.

Abstract
Despite their extreme sensitivity, speckle-based fiber optical sensors are typically limited by the camera frame rate and dynamic range. In this context, recent developments in event-based sensors make them a promising and affordable tool for high-speed interrogation for such class of sensors, offering a low-latency approach to detecting dynamic changes in illumination patterns, well-suited for fast interrogation with frequency response up to the MHz range. In this manuscript, we investigate the potential of using an event-based vision sensor (EVS) as an interrogator for a speckle-based optical fiber sensor operating at 532nm to detect vibrations induced by an off-the-shelf sound speaker. In contact with the fiber, these vibrations induce dynamic changes in the speckle pattern, which are tracked by the EVS and processed to construct temporal frames with timestamps below 100 mu s. Approximating the differential operator of the deformation in the linear regime, we show a successful reconstruction of the acoustic signal for two illustrative case studies: i)a single-frequency signal at 1.2 KHz and ii)a linear ramp between 300 Hz to 2.5 kHz. The results demonstrate the ability to accurately identify not only the fundamental frequencies but also their harmonics generated by the speaker up to 5 KHz, paving an innovative path to harness the potential of speckle-based sensors in multiple scenarios of optical metrology and dynamic sensing applications.