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Publicações

Publicações por CAP

2004

Measurement of the temperature of an optical fiber submitted to an electric arc discharge

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

Publicação
SECOND EUROPEAN WORKSHOP ON OPTICAL FIBRE SENSORS: PROCEEDINGS

Abstract
The radiation emitted by an optical fiber during heating due to an electric arc discharge was detected using a Cronin spectrometer. The fitting of the emission spectrum to the blackbody radiation, allowed the estimation of the temperature range attained by the fiber.

2004

Ring chirped fibre Bragg grating for dynamic dispersion compensation

Autores
Romero, R; Frazao, O; Marques, PVS; Salgado, HM;

Publicação
OPTICS COMMUNICATIONS

Abstract
A dynamic dispersion compensation device using a chirped fibre Bragg grating with a ring geometry embedded in a composite laminated is proposed. A numerical model is presented and compared with the experimental setup. It is shown that the theoretical and experimental results are in good agreement. The tunability of the device is obtained by applying different radius of curvature to the ring structure, and thus producing non-linear variations in the spatial period of the chirped fibre Bragg grating, without changing the usable bandwidth.

2004

Intensity-referenced temperature-independent curvature sensing concept based on chirped gratings embedded in a composite laminate

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

Publicação
SECOND EUROPEAN WORKSHOP ON OPTICAL FIBRE SENSORS: PROCEEDINGS

Abstract
An intensity-referenced temperature-independent curvature measurement technique using a smart composite comprising two chirped fiber Bragg gratings is demonstrated. The two gratings are embedded on opposite sides of a composite laminate and act simultaneously as curvature sensors and as wavelength discriminators, enabling an unambiguous measurement of the composite radius of curvature.

2004

Chirped fibre Bragg grating based multiplexer and demultiplexer for DWDM applications

Autores
Romero, R; Frazao, O; Floreani, F; Zhang, L; Marques, PVS; Salgado, HM;

Publicação
Proceedings of the IASTED International Conference Communication Systems and Networks

Abstract
A multiplexer/demultiplexer for 100 GHz channel spacing based on chirped fibre Bragg gratings with different bandwidths and optical circulators is presented. The spectral characteristics, specifications and operation of these passive devices are described, showing its potential use in DWDM applications.

2004

Optical waveguides fabricated by electron-beam irradiation of Ge-doped flame-hydrolysis silica

Autores
Garcia Blanco, S; Aitchison, JS; Marques, PVS; Taylor, RS; Hnatovsky, C;

Publicação
OSA Trends in Optics and Photonics Series

Abstract
The refractive index distribution and birefringence of electron-beam directly-written waveguides in flame-hydrolysis silica have been characterized by means of micro-reflectivity and mode characterization. These results allow the detail design and fabrication of complex optical devices using this fabrication technique. © 2003 Optical Society of America.

2004

Advanced hybrid sol-gel material processing for higher transparency at 1.5 mu m

Autores
Soppera, O; Moreira, PJ; Marques, PVS; Leite, AP;

Publicação
INTEGRATED OPTICS AND PHOTONIC INTEGRATED CIRCUITS

Abstract
The hybrid sol-gel process is recognized to be an alternative route for production of low cost silica-based integrated optic devices, since it allows the elaboration of ridge waveguides without recourse to high cost processing, like ion etching. However, the high absorption of these materials in the NIR region (1300 and 1550 nm) has limited so far their use. The main objective of this article is to describe the major factors that lead to high losses in the final material and to give solutions to overcome this drawback. The choice of hybrid precursors and the influence of the experimental conditions of gel preparation are of paramount importance. Appropriate synthesis conditions allow a significant decrease of the gel losses (to 0,5 dB/cm) while keeping good wetability and UV-patternability. Each step of the waveguides elaboration was studied separately (UV-irradiation, etching, overcladding, storage) regarding the losses of the material. Post-baking of the waveguides is a way to significantly decrease the losses at 1550 nm. Under appropriate conditions, the losses measured in the waveguides can be kept below 1 dB/cm.

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