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Publications

Publications by Carlos Duarte Viveiros

2017

ECOAL Project-Delivering Solutions for Integrated Monitoring of Coal-Related Fires Supported on Optical Fiber Sensing Technology

Authors
Ribeiro, J; Viveiros, D; Ferreira, J; Lopez Gil, A; Dominguez Lopez, A; Martins, HF; Perez Herrera, R; Lopez Aldaba, A; Duarte, L; Pinto, A; Martin Lopez, S; Baierl, H; Jamier, R; Rougier, S; Auguste, JL; Teodoro, AC; Goncalves, JA; Esteban, O; Santos, JL; Roy, P; Lopez Amo, M; Gonzalez Herraez, M; Baptista, JM; Flores, D;

Publication
APPLIED SCIENCES-BASEL

Abstract
The combustion of coal wastes resulting from mining is of particular environmental concern, and the importance of proper management involving real-time assessment of their status and identification of probable evolution scenarios is recognized. Continuous monitoring of the combustion temperature and emission levels of certain gases allows for the possibility of planning corrective actions to minimize their negative impact on the surroundings. Optical fiber technology is well suited to this purpose and here we describe the main attributes and results obtained from a fiber optic sensing system projected to gather data on distributed temperature and gas emissions in these harsh environments.

2018

Fabrication of Monolithic Add-Drop Filters in Pure Silica by Femtosecond Laser Writing

Authors
Marques, PVS; Amorim, VA; Maia, JM; Alexandre, D; Viveiros, D;

Publication
International Conference on Transparent Optical Networks

Abstract
This paper will review the fabrication of monolithic integrated optical devices by laser direct writing with femtosecond pulsed laser sources, starting with the description of experimental procedures and optimal conditions to fabricate low loss optical waveguides, directional couplers, Y-junctions and first order Bragg gratings by point-by-point writing methods. Finally, the characterization results of a fully operational Add-Drop filter in pure fused silica substrate are described. © 2018 IEEE.

2019

Loss Mechanisms of Optical Waveguides Inscribed in Fused Silica by Femtosecond Laser Direct Writing

Authors
Amorim, VA; Maia, JM; Viveiros, D; Marques, PVS;

Publication
Journal of Lightwave Technology

Abstract

2019

Spectral Tuning of Long Period Fiber Gratings Fabricated by Femtosecond Laser Micromachining through Thermal Annealing

Authors
Viveiros, D; Almeida, JMMMd; Coelho, L; Vasconcelos, H; Amorim, VA; Maia, JM; Jorge, PAS;

Publication
Proceedings

Abstract
A femtosecond laser direct writing system was developed to explore the fabrication of long-period fiber gratings (LPFGs) in SMF28 fibers. The LPFGs, showing the mode LP1,6 at 1500 nm, were exposed to high-temperature annealing up to 950 °C. Modifications in the refractive index (RI) modulation are observed through a blue-shift in the LPFG attenuation bands and above 850 °C, the mode LP1,7 appear at 1600 nm. The wavelength sensitivity to external RI from 1.300 to 1.452 was estimated for both modes before and after annealing. Greater sensitivity was found for the higher order mode in the entire range reaching 2400 nm/RIU around 1.440.

2019

Spectral characteristics of optical waveguides fabricated in glass by femtosecond laser direct writing

Authors
Amorim, VA; Viveiros, D; Maia, JM; Marques, PVS;

Publication
Proceedings of SPIE - The International Society for Optical Engineering

Abstract
The fabrication of optical waveguides with femtosecond laser direct writing is reported in two materials, Suprasil1 and Eagle2000. The influence of typical fabrication parameters, such as pulse energy and scan velocity, on the waveguide's spectral characteristics is explored from 500 to 1700 nm. Tests conducted in Suprasil1 evidence a strong presence of Rayleigh scattering, hindering the production of low-loss waveguides at short wavelengths. On the other hand, optical waveguides fabricated in Eagle2000 exhibited lower insertion losses at short wavelengths, enabling the fabrication of low-loss broadband optical waveguides with a two order of magnitude higher scan velocity when compared with Suprasil1. © 2019 SPIE.

2019

Femtosecond laser micromachining of Fabry-Pérot interferometers in fused silica for refractive index sensing

Authors
Maia, JM; Amorim, VA; Viveiros, D; Marques, PVS;

Publication
Proceedings of SPIE - The International Society for Optical Engineering

Abstract
A Fabry-Pérot interferometer was fabricated inside a fused silica substrate through femtosecond laser micromachining. The influence of the waveguide's writing parameters on the measured signal's quality was studied for an interferometer with a 27-µm wide cavity. Optimal signal-to-noise ratio and fringe visibility were obtained for waveguides written at 75 nJ and 50 µm/s. The same device was characterized with different refractive index liquids, and a maximum sensitivity of 1181.4±23.6 nm/RIU was obtained in the index range of 1.2962 to 1.3828 (at 1550 nm) for the spectral order o?'š = 46. © 2019 SPIE.

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