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About

Recently got a Msc degree in Physics engineering, from Porto University. Currently works at Center of applied photonics at INESCTEC as recearch assistant. Current research lies on advanced Interrogation techniques for optical sensors based on microcavities; Development of low-cost interrogation systems for long-period fiber gratings(LPG) for corrosion sensing in metallic structures. Interrogation techniques using LPG or fiber Bragg gratings (FGB) for health assessment of concrete structures.

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Details

Details

002
Publications

2019

Low-cost interrogation system for long-period fiber gratings applied to remote sensing

Authors
dos Santos, PSS; Jorge, PAS; de Almeida, JMMM; Coelho, L;

Publication
Sensors (Switzerland)

Abstract
We present a portable and low-cost system for interrogation of long-period fiber gratings (LPFGs) costing around a 30th of the price of a typical setup using an optical spectrum analyzer and a broadband light source. The unit is capable of performing real-time monitoring or as a stand-alone data-logger. The proposed technique uses three thermally modulated fiber-coupled laser diodes, sweeping a few nanometers around their central wavelength. The light signal is then modulated by the LPFG and its intensity is acquired by a single photo-detector. Through curve-fitting algorithms the sensor transmission spectrum is reconstructed. Testing and validation were accomplished by inducing variations in the spectral features of an LPFG through changes either in external air temperature from 22 to 425 °C or in refractive index (RI) of the surrounding medium from 1.3000 to 1.4240. A dynamic resolution between 3.5 and 1.9 °C was achieved, in temperatures from 125 to 325 °C. In RI measurements, maximum wavelength and optical power deviations of 2.75 nm and 2.86 dB, respectively, were obtained in the range from 1530 to 1570 nm. The worse RI resolution obtained was 3.47 × 10 -3 . The interrogation platform was then applied in the detection of iron corrosion, expressing wavelength peak values within 1.12 nm from the real value in the region between 1530 and 1570 nm. © 2019 by the authors. Licensee MDPI, Basel, Switzerland.

2018

Real-time Early Warning Strategies for Corrosion Mitigation in Harsh Environments

Authors
Costa Coelho, LCC; Soares dos Santos, PSS; da Silva Jorge, PAD; Santos, JL; Marques Martins de Almeida, JMMM;

Publication
Journal of Lightwave Technology

Abstract
Long period fiber gratings (LPFGs) were coated with iron (Fe) and exposed to oxidation in air and in water having different concentrations of sodium chloride (NaCl) to detect the formation of iron oxides and hydroxides. The process was monitored in real time by measuring the characteristics of the LPFGs attenuation bands. Thin films of Fe were deposited on top of silica (SiO2) substrates, annealed in air, and exposed to water with NaCl. The composition of the oxide and hydroxide layers were analyzed by SEM/EDS and XRD. It was observed the formation of oxide phases, Fe3O4 (magnetite) and Fe2O3 (hematite) when annealing in air, and Fe2(OH)3Cl (hibbingite) and FeO(OH) (lepidocrocite) when exposed to water with NaCl. Results shows that Fe coated LPFGs can be used as sensors for real time monitoring of corrosion in offshore and in coastal projects where metal structures made of iron alloys are in contact with sea or brackish water. In addition, LPFGs coated with hematite were characterized for sensing, leading to the conclusion that the sensitivity to the refractive index of the surrounding medium can be tuned by proper choice of hematite thickness. IEEE

2018

Low-cost interrogation system for long period fiber gratings as sensing devices

Authors
Dos Santos, PSS; Jorge, PAS; De Almeida, JMMM; Coelho, L;

Publication
Optics InfoBase Conference Papers

Abstract
A system with fiber laser diodes and photodetector replaces the usual bulky and expensive systems for characterization of long period fiber gratings and high correlation is achieved when measuring refractive index, temperature and curvature. © OSA 2018 © 2018 The Author(s)