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Publicações

Publicações por Henrique Salgado

2005

Arc-induced long-period gratings

Autores
Rego, G; Marques, PVS; Santos, JL; Salgado, HM;

Publicação
FIBER AND INTEGRATED OPTICS

Abstract
The electric arc technique allows the inscription of long-period gratings (LPGs) virtually in all types of fibers, including non-photosensitive fibers, the case of non-Ge doped photonic crystal fibers being of particular interest. LPGs written in standard fibers using this technique have shown a high thermal stability. Also, the resistance to. - radiation of LPGs arc-induced in pure-silica-core fibers is being assessed and the achieved results are very promising. We have also demonstrated that the combination of arc-induced LPGs and UV-induced fiber Bragg gratings (FBGs) leads to sampled FBGs that are able to address sensing functionalities with enhanced performance. Therefore, as a result of their properties, gratings induced by arc-discharges can find a wide range of applications in optical communications as well as in fiber sensing.

2005

Simultaneous measurement of temperature and strain based on arc-induced long-period fibre gratings

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

Arc-induced long-period gratings in aluminosilicate glass fibers

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

Effect of ionizing radiation on the properties of arc-induced long-period fiber gratings

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

Intensity-referenced and temperature-independent curvature-sensing concept based on chirped fiber Bragg gratings

Autores
Romero, R; Frazao, O; Pereira, DA; Salgado, HM; Araujo, FM; Ferreira, LA;

Publicação
APPLIED OPTICS

Abstract
An intensity-referenced temperature-independent curvature-measurement technique that uses a smart composite that comprises two chirped fiber Bragg gratings is demonstrated. The two gratings are embedded on opposite sides of the composite laminate and act simultaneously as curvature sensors and as wavelength discriminators, enabling a temperature-independent intensity-based scheme to measure radius of curvature. Also, the system's performance is independent of arbitrary power losses that are induced in the lead fibers to the sensing head. It is demonstrated that the measurement range depends on the relative positions of the chirped fiber Bragg gratings and on their spectral bandwidths. By using two chirped fiber Bragg gratings with bandwidths W-1 = 2.8 nm and W-2 = 3.7 nm and with central wavelengths at lambda(01) = 1560.3 nm and lambda(02) - 1563.7 nm, we obtained a resolution of 1.6 mm/(1)Hz for the measurement of the radius of curvature (similar to R = 350 mm) over the measurement range 190 mm < R < infinity. (c) 2005 Optical Society of America.

2010

UWB radio over perfluorinated GI-POF for low-cost in-building networks

Autores
Oliveira, JMB; Silva, S; Pessoa, LM; Coelho, D; Salgado, HM; Castro, JCS;

Publicação
Proceedings - 2010 IEEE International Topical Meeting on Microwave Photonics, MWP 2010

Abstract
This paper presents a performance evaluation of a multiband-orthogonal frequency division multiplexing (MBOFDM) ultra-wideband (UWB) signal transmission over two types of perfluorinated graded-index polymer optical fibers (PFGI-POFs) with diameters of 62.5 µm and 120 µm, using a lowcost optical transceiver. Experimental measurements of packet error rate (PER) and minimum transmitted powers to achieve the maximum allowed PER show that it is possible to have a viable transmission at data rates of 480 Mbps, 200 Mbps and 53.3Mbps over 100, 150 and 200 meters of PF-GI-POF, respectively, preceded by a 1 meter wireless link. ©2010 IEEE.

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