Publications

Publications by José Luís Santos

2000

Fiber optic intensity sensors based on a michelson head configuration with self-referentiation

Authors
Baptista, JM; Santos, JL; Lage, AS;

Publication
LEOS 2000 - IEEE ANNUAL MEETING CONFERENCE PROCEEDINGS, VOLS. 1 & 2

Abstract
Two self-referenced intensity based optical fiber sensors supported on a Michelson sensing head configuration with and without optical feedback are described. Theoretical and experimental studies that demonstrate both sensors are discussed.

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2000

Temperature and strain insensitive bend measurements with D-type fibre Bragg gratings

Authors
Ferreira, LA; Araujo, FM; Santos, JL; Farahi, F;

Publication
14TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS

Abstract
We present a new sensor configuration based on the intrinsic bend sensitivity of Bragg gratings written in D-type fibres. This sensor can be embedded in any layer of a composite material to evaluate curvature in a way independent of axial strain or temperature. It can also be used to measure other parameters such as acceleration, angle or acoustic pressure.

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2000

Investigation of a self-referenced fibre optic intensity sensor supported by a multiple beam Sagnac topology

Authors
Baptista, JM; Santos, JL; Lage, AS;

Publication
14TH INTERNATIONAL CONFERENCE ON OPTICAL FIBER SENSORS

Abstract
A self-referenced fibre optic intensity sensor supported by a multiple beam Sagnac configuration is investigated. Sensor linearity and sensitivity are analysed. Theoretical and experimental results are compared, being considered the sensor design and its optimisation.

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1999

Fiber optic intensity sensors based on Michelson topologies

Authors
Baptista, JM; Santos, JL; Lage, AS;

Publication
1999 SBMO/IEEE MTT-S INTERNATIONAL MICROWAVE AND OPTOELECTRONICS CONFERENCE, PROCEEDINGS, VOLS 1 & 2: WIRELESS AND PHOTONICS BUILDING THE GLOBAL INFOWAYS

Abstract
An investigation is performed on the characteristics of two self-referencing resonant fiber optic intensity sensors supported by a Michelson topology. The sensors are based in transmissive and reflective configurations respectively. Via the definition of the measurement parameter (R parameter) the sensitivity and Linearity of the sensors are analyzed. The problem of sensor design and optimization is considered and the features of the two configurations are addressed.

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1999

Active WDM demodulation scheme for fiber Bragg grating sensors

Authors
Araujo, FM; Ferreira, LA; Santos, JL; Farahi, F;

Publication
FIBER OPTIC AND LASER SENSORS AND APPLICATIONS: INCLUDING DISTRIBUTED AND MULTIPLEXED FIBER OPTIC SENSORS VII

Abstract
A closed loop technique for measuring Bragg wavelength shifts based on active wavelength tuning of a WDM coupler is presented. By stretching the coupling region of a fused biconical WDM, the 3 dB point is set by the feedback loop to always match the reflected Bragg wavelength. With this scheme, sensitivities usually associated with highly selective WDM can be obtained without compromising the measurement range.

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1997

Analysis of the reflective-matched fiber Bragg grating sensing interrogation scheme

Authors
Ribeiro, ABL; Ferreira, LA; Santos, JL; Jackson, DA;

Publication
APPLIED OPTICS

Abstract
A technique for the demodulation of fiber Bragg grating (FBG) sensors based on the use of a second wavelength-matched FBG receiver to track wavelength shifts from the FBG sensor is analyzed, particularly regarding its sensitivity as determined by primary noise sources. Numerical and experimental results show that there is an optimum Bragg wavelength difference between the two FBG's that maximizes the sensitivity for this demodulation technique. (C) 1997 Optical Society of America

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