Conference Agenda

Distributed Acoustic Sensing (DAS) is an optical sensing technology that transforms standard fibre-optic cables into dense arrays of acoustic sensors by measuring dynamic strain along the fibre, commonly using phase-sensitive optical time-domain reflectometry (ϕ-OTDR). This approach is particularly suitable for marine environments, where the deployment of conventional instrumentation is challenging. The MODAS project “Monitoring the Oceans with DAS”, explores the application of DAS in seismology, oceanography, and bioacoustics in the Azores region.

We take advantage of the enhancement of Rayleigh scattering in La-doped fiber to enable evanescent field and external environment interactions. We study how the refractive index of the surrounding medium affects the optical modes and transmitted power in nanoparticle-doped fibers using two sensor configurations. A speckle-pattern due to nanoparticles inside the fiber core was observed and the transmitted power decreased up to -91% when the sensor is fully immersed in oil. Finally, we demonstrate liquid-level measurements across several types of liquids.

A compact fluorescence sensor was adapted to monitor chlorophyll non‑destructively using dual‑wavelength excitation and spectrally resolved detection. The device captures chlorophyll‑dependent red and far‑red fluorescence and shows strong agreement with reference indices (R² > 0.85). Results demonstrate reliable, portable chlorophyll assessment comparable to established instruments.

Nanomembranes can be employed to realize high-performance thermoelectric bolometers for uncooled IR detection in imaging and sensor applications. Design and fabrication of nano-thermoelectric long-wavelength infrared (LWIR) bolometers based on 40–80 nm thick thermoelectric and 20–50 nm thick metallic absorber membranes are presented. The effects of membrane thicknesses, material properties and design parameters on detector responsivity, specific detectivity D* and speed are discussed theoretically and experimentally. The performance of these nano-thermoelectric IR bolometers is compared with those of the state-of-the-art IR detectors, and their noise equivalent temperature difference (NETD) is estimated.

We present a compressive sensing approach for dynamic 3D LiDAR imaging using a single-pixel SiPM detector combined with DMD modulation. The method is designed for photon-limited optical acquisition and accounts for scene motion through a diffeomorphic model. Simulated results show improved reconstruction quality over static compressive sensing in dynamic conditions.