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About

Graduated in Physics - Optics from the University of Minho (1999), he obtained a Masters in Optoelectronics and Laser from Faculty of Science from University of Porto (2003), a PhD in Physics from Faculty of Science from University of Porto (2011). He is Associate Professor in Instituto Politécnico de Viana do Castelo and Senior Researcher at the Applied Photonics Center INESC TEC. It is author and co-author of over 80 scientific articles related to optical fibers sensors, whispering gallery modes and long period grating.

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Publications

2018

Optical Fiber Link Failure Prediction System Based on Long-Period Fiber Grating Mechanical Sensor

Authors
Sotomaior, N; Teixeira, B; Azevedo, J; Caldas, P; Rego, G; Pinto, P;

Publication
Proceedings

Abstract
High data rate optical fiber links are usually deployed in core IP networks to transport bulky [...]

2016

Arc-Induced Long-Period Fiber Gratings in the Dispersion Turning Points

Authors
Colaco, C; Caldas, P; Del Villar, I; Chibante, R; Rego, G;

Publication
JOURNAL OF LIGHTWAVE TECHNOLOGY

Abstract
We demonstrated the possibility to inscribe long-period fiber gratings (LPFGs) in a B/Ge codoped fiber by using grating periods shorter than 150 mu m. We also have arc-induced in the SMF 28 fiber an LPFG in the dispersion turning points by using a grating period of 197 mu m. In previous works, the shortest periods were, respectively, of the order of 190 and 320 mu m for the same fibers. To achieve such a considerable reduction in the grating periods which enables access to the higher order cladding modes (higher sensitivity), we have developed a high-voltage power supply that allows for a constant and stable electric current ranging from 10.5 up to 21 mA. Computer simulations were used to identify the cladding mode resonances for each grating inscribed in the different fibers. The fabricated LPFGs were characterized as a function of the external refractive index from 1.33 up to 1.42, and an average refractive index sensitivity of -720 nm/RIU in the 1.33-1.41 range was obtained for a 192-mu m LPFG without further optimization, such as the use of etching or thin films deposition.

2015

Arc-Induced Gratings in the Turning Points

Authors
Colaco, C; Caldas, P; Chibante, R; Rego, G;

Publication
24TH INTERNATIONAL CONFERENCE ON OPTICAL FIBRE SENSORS

Abstract
We demonstrated the inscription of arc-induced long-period fiber gratings (LPFGs) in the B/Ge co-doped fiber and in the SMF28 fiber by using grating periods shorter than 150 mu m and 200 mu m, respectively. This achievement was a result of the development of a high voltage power supply that allows for a constant and stable electric current ranging from 10.5 mA up to 21 mA. The fabricated LPFGs were characterized as a function of the external refractive index from 1.333 up to 1.420 and a refractive index sensitivity of the order of 1000 nm/RIU was obtained without further optimization.

2015

Cryogenic Temperature Response of Reflection-Based Phase-Shifted Long-Period Fiber Gratings

Authors
Martins, R; Caldas, P; Teixeira, B; Azevedo, J; Monteiro, J; Belo, JH; Araujo, JP; Santos, JL; Rego, G;

Publication
JOURNAL OF LIGHTWAVE TECHNOLOGY

Abstract
In this study, we investigated the temperature behavior of phase-shifted long-period fiber gratings (PS-LPFGs) inscribed in two types of optical fiber: B/Ge and SMF28. The experiments were carried out from 5 to 305 K using a superconducting quantum interference device magnetometer. The average temperature sensitivity obtained of -0.43 nm/K for PS-LPFGs inscribed in the B/Ge fiber is one order of magnitude larger than for PS-LPFGs inscribed in the SMF28 fiber, in the 60-240 K range. Values ranging from -0.08 nm/K up to 0.2 nm/K were obtained in the 5-35 K temperature range, which are considerably better than previous results achieved for metal-coated FBGs and also for LPFGs inscribed in a similar B/Ge codoped fiber. Nevertheless, further work is required in order to correctly address sensor reliability.

2015

Simulation of Long Period Fibre Gratings and Applications

Authors
Baptista, FD; Guerreiro, A; Gomes, LA; Caldas, P;

Publication
PROCEEDINGS OF THE INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS 2014 (ICNAAM-2014)

Abstract
Long-period gratings is class of fiber gratings, in which the period of the refractive index modulation is such that it satisfies a phase matching condition between the fundamental core mode and forward propagating cladding modes of an optical fiber. Many applications in optical communications and optical fiber sensing have been reported along the last years. In this work we present a simulation tool for determining LPG transmission spectrum and the coupling curve. The simulation tool uses MatLab code. The software produces also estimations of the resonant wavelength displacement due to changes in external parameters like temperature or external refractive index. A simple comparison between the simulation and the experimental result show that exist a good agreement with results obtain.