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006
Publications

2019

Bi-core optical fiber for sensing o temperature, strain and torsion

Authors
Lobo Ribeiro, ABL; Silva, SFO; Frazao, O; Santos, JL;

Publication
MEASUREMENT SCIENCE AND TECHNOLOGY

Abstract
Bi-core optical fiber structures are studied for applications in sensing. In this paper, an analysis is performed on the spectral characteristics of light propagating in these fibers with central launching core illumination from a standard single mode fiber. Reflective and transmissive configurations are addressed. The characteristics of a reflective bi-core fiber structure for measurement of strain, temperature and absolute value of torsion are investigated and highlights for further research are presented.

2018

Temperature Compensated Strain Sensor Based on Long Period Gratings and Microspheres

Authors
Ascorbe, J; Coelho, L; Santos, JL; Frazao, O; Corres, JM;

Publication
IEEE Photonics Technology Letters

Abstract

2018

Quantification of Ethanol Concentration in Gasoline Using Cuprous Oxide Coated Long Period Fiber Gratings

Authors
Monteiro Silva, F; Santos, JL; Marques Martins de Almeida, JMMM; Coelho, L;

Publication
IEEE Sensors Journal

Abstract

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

Measurement thermal conductivity of water using a all-fiber sensor based on a metallic coated hybrid LPG-FBG structure

Authors
Silva, GE; Caldas, P; Santos, JL; Santos, JC;

Publication
Optics InfoBase Conference Papers

Abstract
This paper presents preliminary results of common water thermal conductivity measurements using an all-fiber sensor based in conventional hot-wire method concept. The thermal conductivity of common water at room temperature obtained is 0.699 W/mK. Although the result is relatively distinct, about 14%, from the reference value found in literature, it is promising and indicates the feasibility of using the experimental arrangement for measuring thermal properties of materials with higher accuracy, provided that improvements already foreseen in future work be incorporated. © OSA 2018 © 2018 The Author(s)

Supervised
thesis

2016

Analysis of Plasmonics Based Fiber Optic Sensing Structures

Author
Hamed Moayyed

Institution
UP-FCUP

2016

Research and development of optical fibre sensors based on thin film coating technology

Author
Luís Carlos Costa Coelho

Institution
UP-FCUP

2015

Fiber Sensing Based on New Structures and Post-Processing Enhancement

Author
Marta Sofia dos Anjos Ferreira

Institution
UP-FEP