2005
Autores
Rego, G; Marques, PVS; Salgado, HM; Santos, JL;
Publicação
ELECTRONICS LETTERS
Abstract
A study on arc-induced long-period fibre gratings (LPFGs) revealed that their strain sensitivity depends on the electric current of the arc discharge. Based on that property, a sensor scheme comprising two concatenated LPFGs was implemented for discrimination of temperature and strain effects. This sensor presented resolutions of +/-0.1 degreesC/rootHz and +/-35 muepsilon/rootHz, respectively.
2005
Autores
Rego, G; Falate, R; Santos, JL; Salgado, HM; Fabris, JL; Semjonov, SL; Dianov, EM;
Publicação
OPTICS LETTERS
Abstract
Permanent long-period gratings were written using arc discharges in two aluminosilicate fibers, one of which was doped with erbium. Reversible gratings were also mechanically induced in both fibers. The thermal behavior of the arc-induced gratings was investigated at up to 1100 degrees C. It was found that the shift of the resonant wavelengths exhibited a well-defined linear dependence on temperature up to 700 degrees C. (c) 2005 Optical Society of America.
2005
Autores
Rego, G; Fernandez, AF; Gusarov, A; Brichard, B; Berghmans, F; Santos, JL; Salgado, HM;
Publicação
APPLIED OPTICS
Abstract
We experimentally study the effect of ionizing radiation on the properties of long-period gratings fabricated in two pure-silica-core fibers with the arc-discharge technique. It is observed that the spectra of the gratings remain almost unchanged after being subjected to doses in excess of 0.5 MGy. The results also show that the gratings' temperature and strain sensitivities are not affected by gamma radiation. (c) 2005 Optical Society of America.
2005
Autores
Rego, G; Falate, R; Kalinowski, HJ; Fabris, JL; Marques, PVS; Salgado, HM; Santos, JL;
Publicação
17th International Conference on Optical Fibre Sensors, Pts 1 and 2
Abstract
A compact sensor able to discriminate between temperature and strain related effects was implemented. The proposed sensing head comprises a single long-period grating with two sections written consecutively in the SMF-28 fiber, by the electric arc discharge technique, using different fabrication parameters. The sensor performance is based on the distinct temperature and strain sensitivity values presented by two neighbor resonances belonging to each grating section. The temperature and strain resolutions are +/- 0.1 degrees C and +/- 40 mu epsilon, respectively.
2005
Autores
Frazao, O; Ramos, CA; Pinto, NMP; Baptista, JM; Marques, AT;
Publicação
COMPOSITES SCIENCE AND TECHNOLOGY
Abstract
In this paper, we present a novel smart composite based on single mode optical fibres embedded in a hybrid composite laminated. This smart composite comprehended three optical fibres: an optical fibre positioned between two layers of carbon fibres; other optical fibre embedded in two layers of glass fibres; and another optical fibre inserted between the two different composite laminates. Due to cure process using hot plate press, different optical attenuations were obtained for the three optical fibres. The optical fibre positioned between the two different layers (carbon/glass) presented higher losses when compared with the two other optical fibres embedded between equal types of layers. The losses result from the different diameter of carbon/glass and the different coefficient of thermal expansion of the composite material. The smart composite was characterised in terms of its sensitivity to temperature and pressure, independently. Using a matrix method, it was possible to discriminate the pressure and the temperature with only one measurement. Maximum errors of 2.45 degrees C and 0.6 kN/m(2) were found to 60 degrees C and 2500 kN/m(2) measurement ranges.
2005
Autores
Frazao, O; Carvalho, JP; Salgado, HM;
Publicação
MICROWAVE AND OPTICAL TECHNOLOGY LETTERS
Abstract
A simple splice technique to fuse a SMF-28 (TM) and a microstructured fibre using a conventional electric-are splicer is presented. The technique consists in applying the electric arc in the SMF-28 (TM) region. The fusion-loss dependence with arc duration for constant fusion power is also investigated. A splice loss of 0.25 dB is obtained with high rtproducibility. (c) 2005 Wiley Periodicals, Inc.
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