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About

Luís Carlos Costa Coelho received his graduation in Physics Engineering in 2006 and MSc in Instrumentation and Microelectronics in 2007 both by University of Coimbra in Portugal. At the Physics Department of the same University he developed research in Atomic and Nuclear Instrumentation with focus on gaseous scintillation counters towards high energy radiation. In this context he was directly involved in the international experience "Xenon Direct Dark Matter Search" at the National Laboratory of Gran Sasso in Italy, aiming search dark matter through the detection of weakly interacting massive particles. In 2010 he started to working in optical fibre sensors at the Optoelectronics and Electronic Systems of INESC Porto in Portugal, mainly applied to hydrogen detection under the project MICROPHYTE-Metabolic engineering of chlamydomonas and environmental optimization for hydrogen production and release. In 2016 received his Ph.D. degree in Physics at the University of Porto, Porto, Portugal with the focus on thin films technology applied to optical fibre sensors in collaboration with the now Centre for Applied Photonics of INESC TEC, Porto, Portugal. He?s research involves the study of coating types for gases and liquids detection, in particular hydrogen, for refractometers with surface plasmon resonance and for high refractive index samples monitoring with coated long period fibre gratings. He?s current research interests includes bio and chemical sensors based on thin film coating technology of particular structures as long period fibre gratings, fibre Bragg gratings, using surface plasmon resonance phenomenon. He is currently a Post-doc Researcher working in the project MARINEYE at INESC TEC ? A prototype for multitrophic oceanic monitoring developing sensors for dissolved carbon dioxide detection using colorimetric and refractometer platforms combined with new designs of optical fibre structures. In the last few years, he has published more than 47 papers in international journals with referee and over 35 papers in national and international conferences with more than 1350 citations and an h index of 13. He has been referee in a wide range of international journals as IEEE, OSA, SPIE, Elsevier, Pier, MDPI and Springer. He was also the president of the University of Porto SPIE Student Chapter in 2014 and a member of the organization team of the 9th Advanced Study Course on Optical Chemical Sensors and Biosensors (ASCOS 2015). Luis Coelho is a member of SPIE.

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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.

2019

A Simple Spectral Interrogation System for Optical Fiber Sensors

Authors
Santos,; Jorge,; Almeida,; Coelho,;

Publication
Proceedings

Abstract
Optical fiber sensors (OFS) based on long-period fiber gratings (LPFG) or on surface plasmon resonance (SPR) represent attractive solutions for detection systems in remote areas. An interrogation system consisting on wavelength modulation of fiber coupled distributed feedback (DFB) lasers was implemented and tested. The system uses a single photodetector to individually acquire the intensity of each DFB laser modulated by the OFS and the real transmission spectrum is reconstructed through curve fitting. Testing was accomplished by measuring the spectral features of an LPFG when changing the surrounding refractive index and errors lower than 1.8 nm in the 1530 to 1570 nm wavelength region were obtained.

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