Abstract
This study experimentally investigates the impact of EDFA pump power on the State of Polarization (SOP) in optical fiber systems at 1550 nm, with particular relevance for distributed sensing applications. Using a tunable laser and polarimeter, three power levels were tested:-18 dBm,-20 dBm, and-23 dBm. Results show that polarization stability is strongly affected by power: while-18 dBm and-20 dBm provided repeatable SOP and phase behavior,-23 dBm caused significant phase shifts and Stokes parameter drift. Furthermore, for EDFA output powers greater than 0 dBm, the polarization state exhibits a strong dependence on optical power. Despite these effects, Polarization Dependent Gain (PDG) remained low (~ 0.46 dB), confirming the EDFA meets commercial specifications. The study highlights a trade-off where lower input powers, though avoiding saturation, can worsen polarization instability in short fiber systems, which is critical for optical communication and distributed sensing design.

Abstract
Investigating the complex coupling between the lithosphere, atmosphere, and ionosphere (LAI) requires a fundamental understanding of the physical forces governing tectonic processes and their electromagnetic manifestations. While various pre-seismic signals have been successfully identified, a persistent gap remains between the empirical observation of these phenomena and the fundamental physical laws that describe nature across all scales, from the subatomic realm to cosmic expansion. Exploring these interrelations presents significant challenges due to divergent scientific languages, specialized expertise, and unique terminologies across fields. The recently approved COST Action CA24101 "Testing Fundamental Physics with Seismology" (FuSe) aims to bridge this gap by exploring how seismic phenomena and earthquake precursors can serve as a "multi-messenger" window into fundamental interactions.At the heart of FuSe is the belief that imprints of non-standard physics, such as scalar fields or "fifth forces”, may be embedded within seismic and geomagnetic data. Conversely, theoretical insights from fundamental physics can refine our understanding of Earth’s interior by improving models of density and thermodynamic parameters like elasticity and bulk modulus. This refined modeling is essential for accurately interpreting the electromagnetic and gravitational perturbations that occur within the complex Earth-atmosphere-space system.To ensure these breakthroughs translate into practical advancements, FuSe focuses on several strategic pillars:-   Building a common language: developing a shared methodology to equip the next generation of scientists with cross-disciplinary skills.-   Interfacing communities: creating dynamic research groups that unite scientists from particle physics, gravity, planetary science, and seismology.-   Cross-disciplinary data integration: consolidating seismic data from the Earth and Moon with particle physics and geomagnetic data into AI-ready, FAIR-compliant streams.-   SME collaboration: partnering with small and medium-sized enterprises (SME) to advance sensor networks, AI algorithms, and real-time natural catastrophe alert systems.In this presentation, we outline the roadmap of the FuSe Action. We invite researchers with a background in electromagnetic precursors and LAI coupling to join this collaborative environment, where the synergy between geosciences and fundamental physics promises to drive innovative breakthroughs and unlock new paradigms in our comprehension of the Earth and the Universe.This abstract is based upon work from COST Action CA24101, Testing Fundamental Physics with Seismology (FuSe), supported by COST (European Cooperation in Science and Technology).

Abstract
This paper presents the conditions required for effective sensitivity amplification in the optical harmonic Vernier effect. Two distinct cases are analyzed: in the first, the sensor cavity is the shortest, while in the second, it is the longest. Based on the proposed theoretical model, supported by experimental results, it is concluded that, in the first case, the sensitivity associated with the spectral extremes increases with the order of the harmonic states. In contrast, in the second case, the sensitivity at the spectral extremes remains constant, regardless of the harmonic order. To evaluate the effectiveness of applying the optical Vernier effect and to differentiate between the two cases, a new formulation of the magnification factor (M-factor) is introduced. This leads to the definition of a novel figure of merit for the optical Vernier effect, denoted as (FoM(Vernier)). In Case 1, where harmonics are generated by increasing the reference cavity, the figure of merit assumes a value of (m + 1). In Case 2, where harmonics are generated by increasing the sensor cavity, the figure of merit remains constant at 1, regardless of the state order (whether fundamental or harmonic). This study also concludes that the observed increase in sensitivity is apparent rather than intrinsic, as the sensitivity curve produced by the optical Vernier effect mirrors that of a conventional interferometer.

Abstract
Interferometric systems are frequently utilized in metrology due to their enhanced sensitivity, and combining these systems with resonance effects enables advantageous interrogation capabilities. The Fano resonance is a phenomenon that exploits the interplay between interference and resonance. In this research, a cleaved fiber Bragg grating is simulated to demonstrate the possibility of inducing Fano resonance through the interference of Bragg and Fresnel reflections. The device can adjust the asymmetrical spectrum, which can be leveraged as a dynamic sensor for a variety of applications, including polarization-based measurements and remote sensing.

Abstract
Detection of leaks in hydrogen (H2) infrastructure is required on a large scale to enable a safe widespread use of this clean energy source. Sensing solutions must be low-cost, use scalable fabrication methods and allow multiplexed detection while providing reliable safety alarms as fast as possible. Optical methods can make this possible while avoiding the risk of ignition due to electronics at the point of detection. Metal hydride-based micro-mirror configurations benefit from a simple interrogation scheme, as long as the sensitive element can produce a large optical response. Magnesium thin films undergo a drastic variation of properties when hydrogenated, making them suitable for this application. In this work, a micro-mirror device using single-mode fibers capable of detecting the presence of H2 with a loading t10 and t90 of 1.2 and 3.0 s, respectively, is demonstrated. A complete interrogation unit was developed, presenting a solution suited for widespread deployment using industry-standard optical components and equipment.

Abstract
Designing reverse logistics networks requires making cost-emissions-service trade-offs in systems where return flows are irregular and product condition is highly variable, such has circular economy (C.E) oriented business. This paper develops a discrete-event simulation model to compare centralized and localized reverse-logistics configurations for a regional bicycle supply chain. The model captures stochastic task generation, condition-dependent routing into recovery versus recycling streams, and capacity-triggered dispatching on a road-network distance representation. A factorial experiment evaluates eight scenarios with statistical validation of the results. Under the modeled assumptions and dispatch policy, the centralized configuration consistently achieves lower cost and CO2 emissions per completed task while completing more tasks within the simulated horizon. Although the localized configuration reduces total distance traveled, it exhibits higher distance per completed task, indicating that pooling and utilization effects dominate the distance savings associated with additional hubs. These results provide comparative, mechanism-based insights into how network structure and fleet sizing interact with consolidation and dispatch rules in reverse logistics, and motivate future extensions toward adaptive control policies and higher-fidelity facility process modeling in the context of Circular Economy R-Strategies. © ISC 2026.