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Publications

Publications by Pedro Jorge

2015

Magnetic field measurement using a fiber laser sensor in ring arrangement

Authors
Nascimento, IM; Baptista, JM; Jorge, PAS; Cruz, JL; Andres, MV;

Publication
OPTICAL SENSORS 2015

Abstract
In this work an optical fiber laser with loop configuration was developed for magnetic field measurement. The transducer element is an FBG written in a HiBi fiber whose wavelength is modified using a magnetostrictive material that applies deformation in the presence of the magnetic field. The laser has a bandwidth of 450 MHz and operates in single polarization. A shift of 258.5 pm was observed in the laser operating wavelength for a magnetic field of 17.85 mT. Moreover, a maximum sensitivity of 14.72 pm/mT in the linear regime operation was achieved when increasing the magnetic field. The system provides a narrow emission line that is dependent on the magnetic field magnitude enabling high resolution interferometric measurement schemes. The laser response to AC magnetic fields was also characterized using a passive interferometer with higher sensitivity in the range of 8.32 to 17.93 mT(RMS).

2016

MarinEye - A tool for marine monitoring

Authors
Martins, A; Dias, A; Silva, E; Ferreira, H; Dias, I; Almeida, JM; Torgo, L; Goncalves, M; Guedes, M; Dias, N; Jorge, P; Mucha, AP; Magalhaes, C; Carvalho, MDF; Ribeiro, H; Almeida, CMR; Azevedo, I; Ramos, S; Borges, T; Leandro, SM; Maranhao, P; Mouga, T; Gamboa, R; Lemos, M; dos Santos, A; Silva, A; Teixeira, BFE; Bartilotti, C; Marques, R; Cotrim, S;

Publication
OCEANS 2016 - SHANGHAI

Abstract
This work presents an autonomous system for marine integrated physical-chemical and biological monitoring - the MarinEye system. It comprises a set of sensors providing diverse and relevant information for oceanic environment characterization and marine biology studies. It is constituted by a physical-chemical water properties sensor suite, a water filtration and sampling system for DNA collection, a plankton imaging system and biomass assessment acoustic system. The MarinEye system has onboard computational and logging capabilities allowing it either for autonomous operation or for integration in other marine observing systems (such as Observatories or robotic vehicles. It was designed in order to collect integrated multi-trophic monitoring data. The validation in operational environment on 3 marine observatories: RAIA, BerlengasWatch and Cascais on the coast of Portugal is also discussed.

2015

Modal Filtering for Optimized Surface Plasmon Resonance Sensing in Multimode Plastic Optical Fibers

Authors
Cennamo, N; Coelho, L; Santos, DF; Baptista, JM; Guerreiro, A; Jorge, PAS; Zeni, LG;

Publication
IEEE SENSORS JOURNAL

Abstract
In this paper, we present the numerical and the experimental results of a new low cost surface plasmon resonance sensor configuration. It is based on a plasmonic sensor platform and an efficient higher order modes filtering in plastic multimode fibers, exploiting a tapered plastic optical fiber at the output of the sensor system. The experimental results have demonstrated that the tapered filter positioned after the sensor system improves the performances in terms of refractive index range and depth of the resonance curve. The results are in agreement with the numerical simulations.

2015

New Trends on Optical Fiber Tweezers

Authors
Rodrigues Ribeiro, RSR; Soppera, O; Oliva, AG; Guerreiro, A; Jorge, PAS;

Publication
JOURNAL OF LIGHTWAVE TECHNOLOGY

Abstract
In the last few decades, optical trapping has played an unique role concerning contactless trapping and manipulation of biological specimens. More recently, optical fiber tweezers (OFTs) are emerging as a desirable alternative to bulk optical systems. In this paper, an overview of the state of the art of OFTs is presented, focusing on the main fabrication methods, their features and main achievements. In addition, new OFTs fabricated by guided wave photo polymerization are reported. Their theoretical and experimental characterization is given and results demonstrating its application in the manipulation of yeast cells and the organelles of plant cells are presented.

2016

Noveloptical current sensor for metering and protection in high power applications

Authors
Nascimento, IM; Brigida, ACS; Baptista, JM; Costa, JCWA; Martinez, MAG; Jorge, PAS;

Publication
INSTRUMENTATION SCIENCE & TECHNOLOGY

Abstract
A clamp-on optical current sensor prototype for metering and protection applications in high power systems was developed and characterized. The system is based on the Faraday effect in a low birefringence, high Verdet constant, 8cm long SF57 Schott glass prism. It was incorporated in a nylon casing suitable for clamp-on applications in the power line. The sensor operation was tested at 630nm, 830nm, and 1550nm to access its applicability in remote interrogation via fiber links. Optimal operation at 830nm is reported with a linear response up to 65.28kA, with 0.1 or 0.2 accuracy class considering a nominal currents of 1.2 and 0.3 kA (root mean square), respectively. Twelve calibrations procedures performed over six days showed an estimated maximum error of 11m A. Preliminary measurements were made from 40 to 400Hz. The sensor was exposed to transient signals less than 10 mu s that demonstrated its use in protection applications.

2015

On the anodic aluminium oxide refractive index of nanoporous templates

Authors
Hierro Rodriguez, A; Rocha Rodrigues, P; Valdes Bango, F; Alameda, JM; Jorge, PAS; Santos, JL; Araujo, JP; Teixeira, JM; Guerreiro, A;

Publication
JOURNAL OF PHYSICS D-APPLIED PHYSICS

Abstract
In the present study, we have determined the intrinsic refractive index of anodic aluminium oxide, which is originated by the formation of nanoporous alumina templates. Different templates have been fabricated by the conventional two-step anodization procedure in oxalic acid. Their porosities were modified by chemical wet etching allowing the tuning of their effective refractive indexes (air-filled nanopores + anodic aluminium oxide). By standard spectroscopic light transmission measurements, the effective refractive index for each different template was extracted in the VIS-NIR region. The determination of the intrinsic anodic aluminium oxide refractive index was performed by using the Maxwell-Garnett homogenization theory. The results are coincident for all the fabricated samples. The obtained refractive index (similar to 1.55) is quite lower (similar to 22%) than the commonly used Al2O3 handbook value (similar to 1.75), showing that the amorphous nature of the anodic oxide structure strongly conditions its optical properties. This difference is critical for the correct design and modeling of optical plasmonic metamaterials based on anodic aluminium oxide nanoporous templates.

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