2001
Autores
Baptista, JM; Frazao, O; Felix, C; Ferreira, LA; Araujo, FM; Santos, JL; Lage, A; Figueiras, JA;
Publicação
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
Autores
Baptista, JM; Santos, JL; Lage, AS;
Publicação
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.
2001
Autores
Teixeira, ALJ; Lima, MJN; Frazao, O; da Rocha, JRF;
Publicação
ICTON 2001: 3RD INTERNATIONAL CONFERENCE ON TRANSPARENT OPTICAL NETWORKS, CONFERENCE PROCEEDINGS
Abstract
Fiber Bragg Gratings (FBG's) are nowadays widely used in various fields, including telecommunications. Since emergence, this component has found many applications due to its properties, versatility and variety of controllable parameters that can shape in various manners its spectral properties. These devices have the advantage of being built of fiber and they are widely used in mono and multichannel networks.
2001
Autores
Andre, PS; Pinto, JL; Abe, I; Kalinowski, HJ; Frazao, O; Araujo, FM;
Publicação
Journal of Microwaves and Optoelectronics
Abstract
This paper presents some aspects of the production, characterization and implementation of fibre Bragg grating as a key element for selective filtering in optical communications. Theory, fabrications and applications of the Fibre Bragg grating for a specific tuneable optical add-drop multiplexer (OADM) are presented. The OADM performance on a 2.48832 Gbit/s dense wavelength division multiplexing optical communications system with 95 km is reported. The power penalty for the removed channels was less than 0.1 dB. We obtain good agreement between the FBG behaviour the OADM performance with the numerical simulations results. Copyright SBMO.
2001
Autores
Frazao, O; Araujo, FM; Vieira, A; Correia, N; Novo, C; Costa, AN; Marques, AT;
Publicação
COMPOSITES IN CONSTRUCTION
Abstract
This paper presents a smart composite for structural monitorisation, based on fibre Bragg grating sensors. The sensor plate, a carbon fibre reinforced plastic laminate having an embedded optical strain gauge rosette, was designed, produced, and tested. These instrumented carbon fibre laminates can be used for monitoring of reinforcement and protection of structures, playing an important role in the control of repaired constructions. The smart structures developed are shown to have the ability of measuring temperature and strain.
2001
Autores
Frazao, O; Rego, G; Lima, M; Teixeira, A; Araujo, FM; Andre, P; da Rocha, JF; Salgado, HM;
Publicação
LONDON COMMUNICATIONS SYMPOSIUM 2001, PROCEEDINGS
Abstract
We have flattened the gain spectrum of a commercial Erbium-doped fibre amplifier, obtaining a curve with approximately 3 dB of ripple, from 1524 nm to 1551 nm, using long-period fibre gratings as equalising optical filters. The fabrication principle of the long-period fibre grating is based on the electric arc technique.
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