Abstract
A fibre Bragg grating sensing configuration is presented for simultaneous measurement of strain and temperature. The proposed concept relies on writing a single Bragg grating on the splice region of two fibres with different levels of germanium doping. Doing so, a grating structure appears with three resonance peaks, which show distinct temperature sensitivities but similar strain responses. The experimental validation of the concept indicated resolutions of +/-1.5 degreesC Hz(-1/2) and +/-5.6 muepsilon Hz(-1/2) over measurement ranges of 80 degreesC and 1000 muepsilon for temperature and strain, respectively.

Abstract
We used a pair of Bragg gratings written in high birefringence fibre optics to measure, simultaneously, longitudinal and transverse strain and temperature. The Bragg gratings are superimposed in the same position of the fibre optic, so as to behave as a punctual sensor. The sensitivity of the spectral response of the device to longitudinal strain, transverse strain and temperature are all characterized, and the results of its application as a three-parameter sensor are also presented.

Abstract
An optical fiber sensing system, for monitoring oxygen aiming in vivo nuclear magnetic resonance (NMR) applications is presented. Oxygen detection is based on the dynamic quenching of the fluorescence of a ruthenium complex trapped in the porous structure of a sol-gel silica film. Oxygen concentration is determined by phase-modulation fluorometry. Preliminary results concerning the characterization of doped sol-gel thin films deposited by dip coating in glass slides and in optical fiber probes are presented. Four different probe configurations are tested and compared. Best results are obtained with a fiber taper configuration which shows reproducibility and best excitation efficiency. This structure is fully characterized and some considerations regarding optimal fiber optical sensing probes for 02 detection are addressed.

Abstract
In this study an optical fibre sensor system was conceived for simultaneous detection of the strain and the acoustic emission due to damage. It consists of a fibre Bragg grating and a Fabry-Perot interferometer. For the interrogation of the Fabry-Perot cavity, an innovative low cost process based on the generation of two quadrature phase-shifted signals using two fibre Bragg gratings was implemented, allowing the recovery of the change in the cavity length. An automated processing system, based on Kohonen's self-organizing maps is also presented, for future classification of the acoustic emission waves detected by the optic fibre sensor.

Abstract
We present and demonstrate a high-resolution absolute-distance measurement system based on multiple-wavelength interferometry. The information on a cavity length is obtained by sampling a fringe of its spectral response at different wavelengths. This is achieved by simultaneously tuning multiple fiber Bragg gratings. For a two wavelength system, an unambiguous measurement range of 262 µm was obtained with a resolution of 14.3 nm.

Abstract
A sensing head for simultaneous measurement of temperature and strain is presented and analyzed. The proposed configuration is based on the combination of two Bragg gratings, written in different fibres and with different reflectivities, to form a single signature with a reflected step spectrum profile. By measuring the changes in the peak wavelength and spectral width of this signature, resolutions of 0.65 degreesC/rootHz and +/- 2.55 muepsilon/rootHz were achieved for temperature and strain measurements, respectively.