2000
Authors
Jauregui, C; Araujo, FM; Ferreira, LA; Santos, JL; Lopez Higuera, JM;
Publication
Proceedings of SPIE - The International Society for Optical Engineering
Abstract
An all fiber technique for interrogation of interferometric low-finesse Fabry-Perot cavities is presented. It is based on the modulation of the spectral transfer function of a wavelength division multiplexer. Results are given when both serrodyne and sinusoidal modulation formats are considered.
1999
Authors
Baptista, JM; Santos, JL; Lage, AS;
Publication
Conference Proceedings - Lasers and Electro-Optics Society Annual Meeting-LEOS
Abstract
A sensor based on a Sagnac topology in reflection is described. The sensor uses the properties of its frequency response in order to obtain a self-referenced signal proportional to the measured signal. The sensor is a versatile structure for the monitoring of static and dynamic physical parameters, which require a small number of optical components and simple signal processing.
1991
Authors
Santos, JL; Jackson, DA;
Publication
Optics Communications
Abstract
We describe a scheme in which a multimode laser diode, with effective coherence length less than 250 µm, is used to illuminate sensors multiplexed in time and with their status read by coherence sensing. Data is presented which shows that the spectral characteristics of the laser light remain essentially unchanged upon direct modulation of the laser injection current or whilst subject to laser feedback. This has allowed the multiplexing scheme network to be implemented without recourse to either a Bragg cell modular or an optical isolator. The technique was applied to measure displacement, strain and temperature. © 1991.
1990
Authors
Santos, JL; Farahi, F; Newson, TP; Jackson, DA;
Publication
Proceedings of SPIE - The International Society for Optical Engineering
Abstract
A time division multiplexing technique is described in which the frequency of a laser source is modulated with a sampled ramp. The concept is demonstrated with two Mach-Zehnder interferometers in a parallel configuration, separated by a fibre delay line whose length is determined by the characteristics of the sampling waveform. Pseudo-heterodyne processing was used to recover the phase information from each interferometer. The expansion of the technique to a combined frequency and time division multiplexed fibre-optic sensing system is considered.
1990
Authors
Santos, JL; Farahi, F; Newson, TP; Jackson, DA;
Publication
Optics Communications
Abstract
A time division multiplexing technique is described in which the frequency of a laser source is modulated with a sampled ramp. The concept is demonstrated with two Mach-Zehnder interferometers in a parallel configuration, separated by a fibre delay line whose length is determined by the characteristics of the sampling waveform. Pseudo-heterodyne processing was used to recover the phase information from each interferometer. The expansion of the technique to a combined frequency and time division multiplexed fibre-optic sensing system is considered. © 1990.
2010
Authors
Santos, JL; Culshaw, B; Lopez Higuera, JM; MacPherson, WN;
Publication
FOURTH EUROPEAN WORKSHOP ON OPTICAL FIBRE SENSORS
Abstract
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