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Tutorial A1: Nonlinear Effects in Optical Fibers for Sensing (Dr. Ali Masoudi, University of Southampton, UK)

In this workshop, we will explore the critical role of nonlinear effects in optical fibers for distributed sensing applications. We will start with a brief introduction to distributed sensing and the scattering mechanisms in optical fibers. Following this, we will delve into key nonlinear effects, including Stimulated Brillouin Scattering (SBS), Stimulated Raman Scattering (SRS), and modulation instability. We will examine the adverse impacts of these nonlinearities on linear Distributed Optical Fiber Sensors (DOFS) such as Raman and Rayleigh-based distributed sensors. The workshop will then focus on Brillouin Optical Time-Domain Analysis (BOTDA) systems, which harness SBS to achieve a Brillouin gain spectrum with a high signal-to-noise ratio (SNR). We will discuss the sensing principles of BOTDA systems and compare different system architectures.  Additionally, a brief overview of Brillouin Optical Correlation-Domain Analysis (BOCDA) systems and their operating principles will be provided. We will conclude with insights on the advantages of leveraging nonlinear effects in advanced sensing technologies.

Tutorial A2: Signal Processing in Distributed Fiber Optic Sensing (Dr. Hugo Martings, Consejo Superior de Investigaciones Científicas -CSIC, Spain)

The whole is greater than the sum of its parts. DFOS allow for a single interrogator to measure a large number of points, but specific and key advantages can be further gained from processing DFOS as a coherent network array of sensors. Effective image denoising algorithms have been demonstrated in BOTDA, since instrumental noise will affect all channels similarly. Pulse coding techniques allow for gains of SNR that surpass those of simple averaging. In DAS, using the coherency of signals arriving to multiple channels, the fiber position in the field (and physical location of noise sources relative to it) can be mapped, and measurements with sensitivity below ambient noise can be performed. With the addition of a full new dimension (space), a multitude of waves can be mapped in seismology, even when overlapping in the same frequency band. We will review signal processing considerations specific to DOFS.

Tutorial B1: Pocket-sized Optical Spectroscopy: Revolutionizing Food Analytics at your Fingertips (Dra Anna G. Mignani and Dr. Leonardo Ciaccheri, National Research Council of Italy (CNR), Institute of Applied Physics “Nello Carrara”CNR, Italy)

Optical spectroscopy is transforming food analysis by providing a cost-effective and eco-friendly alternative to traditional methods. With its ability to deliver rapid and non-destructive measurements without the need for harmful chemicals or solvents, it allows green analytics for food quality and safety assessment. By integrating chemometrics or AI-powered algorithms, optical spectroscopy can decode complex data and perform simultaneous analysis of multiple food components. A single flash of light, combined with advanced spectroscopic training, enables comprehensive quantitative and qualitative assessments of various nutraceutical indicators in one go. It’s an intelligent and sustainable solution for achieving superior food quality and safety standards. Photonic technologies initially developed for telecommunications, generated an explosion of compact light sources, detectors, micro-spectrometers, spectral sensors, fiber optics, and micro-photonic components. These innovations are now transforming food control, providing compact, robust, and low-cost instruments that are perfect for online applications by users with minimal technical training, as well as by consumers. In this tutorial, we will show the the latest and most compact optical spectroscopy devices, with a special attention to those operating in the near-infrared, and to pocket-sized and smartphone-connected models. We will show their applications in food analysis and showcase their potential through a live demo. Get ready to see how these powerful tools can revolutionize food multi-component analyses, and discover opportunities for future collaborations.

Tutorial B2: Towards a Uniform Metrological Assessment of the Performance of Optical Fiber Sensors in Real-Life Contexts (Dr. Francesco Chiavaioli, National Research Council of Italy (CNR), Institute of Applied Physics “Nello Carrara”, Italy)

Optical fiber sensors (OFSs) are dramatically spreading worldwide not only in the scientific research, but also in the industrial market. Given their peculiarities, OFSs are applied to countless different applications, such as physics, engineering, material science, biochemistry and medicine. However, it is still very cumbersome to uniformly compare their performance. Therefore, there is an urgently need for defining the fundamentals of metrological parameters to uniformly assess the performance of optical fiber sensors, and hence to make the their comparison easier. The tutorial will encompass commonly-used performance parameters (sensitivity, resolution, limit of detection, selectivity) and some other parameters of generic interest (accuracy, stability, repeatability and reproducibility). Common mistakes still present in the literature will also be highlighted. The concepts discussed can be applied to any resonance-based sensor, thus providing the basis for an easier and direct performance comparison of a great number of sensors published in the literature up to now.