Publications

Publications by Orlando Frazão

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.

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2004

Simultaneous measurement of temperature and strain using a step spectrum profile fibre Bragg grating arrangement

Authors
Frazao, O; Romero, R; Araujo, FM; Ferreira, LA; Santos, JL;

Publication
SECOND EUROPEAN WORKSHOP ON OPTICAL FIBRE SENSORS: PROCEEDINGS

Abstract
A sensing head for simultaneous measurement of temperature and strain is presented and analyzed. The proposed configuration is based on the combination of two Bragg gratings, written in different fibres and with different reflectivities, to form a single signature with a reflected step spectrum profile. By measuring the changes in the peak wavelength and spectral width of this signature, resolutions of 0.65 degreesC/rootHz and +/- 2.55 muepsilon/rootHz were achieved for temperature and strain measurements, respectively.

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2003

Load cell for structural monitoring based on a microbend self-referenced fiber optic intensity sensor

Authors
Baptista, JM; Frazao, OJ; Ferreira, LA; Araujo, FM; Santos, JL; Lage, AS;

Publication
2003 IEEE LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS, VOLS 1 AND 2

Abstract
A novel microbend optical fiber sensing head embedded in Carbon Fiber Reinforced Plastic (CFRP) was developed. The sensor demonstrated its capability of measuring applied pressure up to 750 kPa.

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2002

Characterization of FBGs written in HiBi IEC fibre for multiparameter sensors

Authors
Abe, I; Schiller, MW; Nogueira, RN; Lopes, P; Frazao, O; Santos, JL; Pinto, JL; Kalinowski, HJ;

Publication
2002 IEEE/LEOS ANNUAL MEETING CONFERENCE PROCEEDINGS, VOLS 1 AND 2

Abstract
A simulation characterization with FEM was made, showing that the HiBi fibre was sensitive to different applied load angles. As such, the experimental data for transversal strain was assessed and the obtained sensibility values were in accordance with the simulation results. The collected data enable the complete characterization of the HiBi FBG, showing its capability to be used as a multiparameter sensor.

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2009

Stimulated Raman Scattering and its Applications in Optical Communications and Optical Sensors

Authors
Baptista, JM; Costa, JW; Barbero, AP; Martinez, MA; Salgado, HM; Marques, MB; Rocco Giraldi, MM; Correia, C; Frazao, O;

Publication
The Open Optics Journal

Abstract

2009

Brillouin Effects in Distributed Raman Amplifiers under Saturated Conditions

Authors
Rocco Giraldi, MTMR; Rocha, AM; Neto, B; Correia, C; Segatto, MEV; Pontes, MJ; Barbero, APL; Costa, JCW; Martinez, MAG; Frazao, O; Baptista, JM; Salgado, HM; Marques, MB; Teixeira, ALJ; Andre, PS;

Publication
2009 SBMO/IEEE MTT-S INTERNATIONAL MICROWAVE AND OPTOELECTRONICS CONFERENCE (IMOC 2009)

Abstract
This paper analyzes experimentally the limitations observed in lightwave systems using distributed Raman amplifiers operating under large pump power input conditions. The Brillouin effect is observed as the pump power becomes equal to watt centered in a specific pump wavelength. The presence of Brillouin peaks degrades the system performance. The Raman amplifier is set with singlemode and dispersion compensating fibers and evaluated in a high capacity WDM link at transmission rates up to 40 Gb/s per channel. The dispersion compensation was accomplished by adjusting the length of the dispersion compensating fiber. The system and amplifier characterization were developed in terms of the on-off gain, ripple, optical signal-to-noise ratio, eye diagram and extinction ratio.

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