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Publications

Publications by CAP

2001

Twin all-optical magnetic probe for current metering and relaying applications

Authors
Caldas, P; Jorge, PAS; Ferreira, LA; Lobo Ribeiro, AB; Santos, JL;

Publication
2001 IEEE Porto Power Tech Proceedings

Abstract
A twin polarimetric configuration based on the Faraday effect for the measurement of electric currents in high voltage environments is presented. Field test results are shown that indicate the device suitability for current metering and relaying applications. © 2001 IEEE.

2001

Passive interrogation of low-finesse Fabry-Perot cavities using fiber Bragg gratings

Authors
Dahlem, M; Santos, JL; Ferreira, LA; Araujo, FM;

Publication
IEEE PHOTONICS TECHNOLOGY LETTERS

Abstract
An investigation on the application of fiber Bragg gratings for the interrogation of interferometric low-finesse Fabry-Perot cavities is reported. The proposed scheme is based on the generation of two quadrature phase-shifted signals that allows the recovering of the change in the cavity length. Besides being totally passive, this technique offers a high degree of flexibility and has the potential to be used in the interrogation of very short cavities.

2001

Interrogation of low-finesse Fabry-Perot cavities based on modulation of the transfer function of a wavelength division multiplexer

Authors
Misas, CJ; Araujo, FMM; Ferreira, LA; Santos, JL; Lopez Higuera, JM;

Publication
JOURNAL OF LIGHTWAVE TECHNOLOGY

Abstract
A theoretical and experimental investigation is reported on a novel all-fiber technique for interrogation of interferometric low-finesse Fabry-Perot cavities, It is based on the modulation of the spectral transfer function of a wavelength-division multiplexer, Results are given when both serrodyne and sinusoidal modulation formats are considered.

2001

Multiplexing of fibre optic intensity sensors using fused biconical wavelength selective couplers

Authors
Abad, S; Araujo, FM; Ferreira, LA; Santos, JL; Lopez Amo, M;

Publication
ELECTRONICS LETTERS

Abstract
Fused biconical wavelength division multiplexers have been used to replace standard couplers in an intensity-sensor multiplexing network. The wavelength-selective power splitting and the low insertion losses of these devices (< 0.2dB) improve the power budget, while providing network overall optical isolations > 30dB. With this isolation, crosstalk effects in the network are proven to be negligible.

2001

Novel self-referenced microbend optical fibre sensor as a load cell for structural monitoring

Authors
Baptista, JM; Frazao, O; Felix, C; Ferreira, LA; Araujo, FM; Santos, JL; Lage, A; Figueiras, JA;

Publication
COMPOSITES IN CONSTRUCTION

Abstract
In this paper we present a novel microbend optical fibre sensor embedded in composite material, which acts as a load cell for structural monitoring in civil engineering. The sensing system is based on a self-referenced fibre optic intensity sensor supported by a Michelson topology with optical feedback. The sensing system is tested in a sand testing bed for different values of load. Results are presented and discussed.

2001

Measurement of refractive index in oils using a self-referenced fiber optic intensity sensor

Authors
Baptista, JM; Santos, JL; Lage, AS;

Publication
LEOS 2001: 14TH ANNUAL MEETING OF THE IEEE LASERS & ELECTRO-OPTICS SOCIETY, VOLS 1 AND 2, PROCEEDINGS

Abstract
A sensor for measurement of refractive index in oils was discussed. The sensor comprised a fiber based-device sensing head placed in a self-referenced fiber optic intensity sensor. The sensing head works on the principle of change of the refractive index of the medium that surrounds the unclad portion of multimode fiber. This results in different attenuation of the guided modes that propagate in the fiber. The injection current of the optical source was swept in frequency to obtain the transfer function.

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