Publications

Publications by Orlando Frazão

2010

<title>Fibre optic remote sensing based on long period gratings with in situ optical source</title>

Authors
Viegas, D; Carvalho, JP; Coelho, L; Santos, JL; Ferreira, LA; Araújo, FM; Frazão, O;

Publication
Fourth European Workshop on Optical Fibre Sensors

Abstract

2011

<title>Modal interferometric sensor based in a birefringent boron-doped microstructured fiber</title>

Authors
Statkiewicz-Barabach, G; Carvalho, JP; Frazão, O; Olszewski, J; Mergo, P; Santos, JL; Urbanczyk, W;

Publication
International Conference on Applications of Optics and Photonics

Abstract

2010

Fibre Optic Hot-Wire Flowmeter Based on a Metallic Coated Hybrid LPG-FBG Structure

Authors
Caldas, P; Jorge, PAS; Rego, G; Frazao, O; Santos, JL; Ferreira, LA; Araujo, F;

Publication
FOURTH EUROPEAN WORKSHOP ON OPTICAL FIBRE SENSORS

Abstract
In this work an all optical hot-wire flowmeter based on a silver coated fibre incorporating a long period grating and a Bragg grating is demonstrated. Optical energy at 1480 nm propagating down the fibre is coupled by the long period grating into the fibre cladding and absorbed by the metallic coating deposited on the fibre surface over the Bragg grating position. This absorption acts like a hot-wire raising locally the fibre temperature, which is effectively detected by the FBG resonance shift. The temperature raise depends on the flow speed of the surrounding air that has the effect to cool the fibre. In this way, the FBG Bragg wavelength shift can be related with the flow speed. Results obtained demonstrate the working principle and a flow speed resolution of 0.08 m/s is demonstrated.

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2006

Brillouin fibre laser sensor for strain and temperature discrimination

Authors
Frazao, O; Marques, JM; Santos, JL; Marques, MB; Baptista, JM;

Publication
Optics InfoBase Conference Papers

Abstract
In this work, a Brillouin fibre laser sensor for strain and temperature discrimination is presented. The fibre laser sensor consists in a Fabry-Pérot cavity with 20 meters of optical fibre between two Bragg gratings. © 2006 OSA/OFS 2006.

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2006

Intensity-referenced sensing system for refractive index measurement

Authors
Frazao, O; Ferreira, LA; Araujo, FM; Santos, JL; Guedes Valente, LC;

Publication
Optics InfoBase Conference Papers

Abstract
A fiber sensing system is presented that allows simultaneous measurement of both refractive index and temperature while providing passive referencing to intensity fluctuations. © 2006 OSA/OFS 2006.

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2011

Fabry-Perot cavity based on a diaphragm-free hollow-core silica tube

Authors
Ferreira, MS; Coelho, L; Schuster, K; Kobelke, J; Santos, JL; Frazao, O;

Publication
OPTICS LETTERS

Abstract
A Fabry-Perot (FP) cavity of simple design and based on a pure silica diaphragm-free hollow tube is proposed. Its operation is based on a first reflection of light at the end of the single-mode fiber that illuminates the silica rod and in a second reflection that takes place at the end of the rod. The FP cavity is characterized for high temperature, pressure and refractive index sensing, showing useful characteristics for the measurement of these three parameters. The diaphragm-free configuration simplifies the measurement of the refractive index of fluids. (C) 2011 Optical Society of America

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