2015
Authors
Lopez Aldaba, A; Rodrigues Pinto, AMR; Lopez Amo, M; Frazao, O; Santos, JL; Baptista, JM; Baierl, H; Auguste, JL; Jamier, R; Roy, P;
Publication
SENSORS
Abstract
A hybrid Fabry-Perot cavity sensing head based on a four-bridge microstructured fiber is characterized for temperature sensing. The characterization of this cavity is performed numerically and experimentally in the L-band. The sensing head output signal presents a linear variation with temperature changes, showing a sensitivity of 12.5 pm/degrees C. Moreover, this Fabry-Perot cavity exhibits good sensitivity to polarization changes and high stability over time.
2015
Authors
Nascimento, IM; Baptista, JM; Jorge, PAS; Cruz, JL; Andres, MV;
Publication
SENSORS AND ACTUATORS A-PHYSICAL
Abstract
An erbium doped (Er3+) fiber optic laser is proposed for magnetic field measurement. A pair of FBGs glued onto a magnetostrictive material (Terfenol-D rod) modulates the laser wavelength operation when subject to a static or a time dependent magnetic field. A passive interferometer is employed to measure the laser wavelength changes due to the applied magnetic field. A data acquisition hardware and a Lab VIEW software measure three phase-shifted signals at the output coupler of the interferometer and process them using two distinct demodulation algorithms. Results show that sensitivity to varying magnetic fields can be tuned by introducing a biasing magnetic field. A maximum error of 0.79% was found, for magnetic fields higher than 2.26 mT(RMS).
2015
Authors
Cennamo, N; Coelho, L; Santos, DF; Baptista, JM; Guerreiro, A; Jorge, PAS; Zeni, LG;
Publication
IEEE SENSORS JOURNAL
Abstract
In this paper, we present the numerical and the experimental results of a new low cost surface plasmon resonance sensor configuration. It is based on a plasmonic sensor platform and an efficient higher order modes filtering in plastic multimode fibers, exploiting a tapered plastic optical fiber at the output of the sensor system. The experimental results have demonstrated that the tapered filter positioned after the sensor system improves the performances in terms of refractive index range and depth of the resonance curve. The results are in agreement with the numerical simulations.
2015
Authors
Ribeiro, RSR; Soppera, O; Viegas, J; Guerreiro, A; Jorge, PAS;
Publication
COMPLEX LIGHT AND OPTICAL FORCES IX
Abstract
In this work, the trapping efficiency of new fiber optical tweezers structures fabricated using photo polymerization and focused ion beam milling techniques is evaluated. The first fabrication methods may present limited capabilities on the tailoring of the structures, and therefore limited operation features. On the other hand, with focused ion beam milling a vast myriad of structures may be accurately fabricated, and contrarily to conventional fabrication methods, more specialized manipulation tools can be developed. In this regard, the performance of FOT for the trapping of yeast cells using spherical lenses (photo polymerization) and spiral phase lenses (FIB) will be presented. In addition, finite difference time domain (FDTD) simulations of the full vectorial optical propagation through the designed structures and the corresponding calculation of the optical forces are presented and different designs are evaluated.
2015
Authors
Nascimento, IM; Baptista, JM; Jorge, PAS; Cruz, JL; Andres, MV;
Publication
OPTICAL SENSORS 2015
Abstract
In this work an optical fiber laser with loop configuration was developed for magnetic field measurement. The transducer element is an FBG written in a HiBi fiber whose wavelength is modified using a magnetostrictive material that applies deformation in the presence of the magnetic field. The laser has a bandwidth of 450 MHz and operates in single polarization. A shift of 258.5 pm was observed in the laser operating wavelength for a magnetic field of 17.85 mT. Moreover, a maximum sensitivity of 14.72 pm/mT in the linear regime operation was achieved when increasing the magnetic field. The system provides a narrow emission line that is dependent on the magnetic field magnitude enabling high resolution interferometric measurement schemes. The laser response to AC magnetic fields was also characterized using a passive interferometer with higher sensitivity in the range of 8.32 to 17.93 mT(RMS).
2015
Authors
Oliveira, LM; Carvalho, MI; Nogueira, EM; Tuchin, VV;
Publication
JOURNAL OF BIOMEDICAL OPTICS
Abstract
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