Abstract
The use of semiconductor nano-particles as temperature probes in luminescence chemical sensing applications is addressed. Temperature changes the intensity, the peak wavelength and the spectral width of the quantum dots luminescent emission in a linear and reversible way. Results are presented that show the feasibility of implementing a self-referenced intensity-based sensor to perform temperature measurements independent of the optical power level in the sensing system. A resolution of 0.3 degrees C was achieved. In addition, it is demonstrated that self-referenced temperature measurements at multiple points could be performed using reflection or transmission based optical fibre configurations.

Abstract
In this study an optic fibre system for health monitoring of fibre reinforced plastics was developed. It is based on the detection of acoustic emission (AE) waves in a loaded material. A low-finesse Fabry-Perot interferometer sensor is used as alternative to the conventional piezoelectric transducers for AE waves sensing. An original procedure for optical fibre sensor interrogation is proposed.

Abstract
A fiber-sensing scheme with controlled sensitivity comprising a fiber Bragg grating (FBG) and a mechanically induced long-period fiber grating (MLPFG) is presented. The FBG was written by exposing the fiber to 248-nm UV laser radiation such that the Bragg wavelength is localized on the slope of a resonant band of a mechanical grating, which was produced by winding a nylon string around a fiber/grooved tube set. The strength of that resonant band was altered by applying loads to the MLPFG. For different loads, the FBG was submitted to strain values of up to 2200 mu epsilon, in steps of 200 mu epsilon, during which the Bragg wavelength and the respective transmitted peak power through the MLPFG were recorded. It was demonstrated that by applying a weight with a value of 0.78 kg to the MLPFG, the sensitivity of the FBG interrogation technique to strain variations increased from 2.23 (without load) to 3.20 pW/mu epsilon.

Abstract
We have investigated the polarization properties of long-period fibre gratings fabricated using the electric arc technique. It was found that the choice of the fabrication parameters (electric current, arc duration and pulling tension) affects the polarization dependent loss of the produced gratings. In particular, a non-monotonic dependence on the external pulling tension was obtained.

Abstract
The underlying formation mechanisms and the properties of long-period gratings produced through arc discharges are intrinsically related to the temperature reached by the fibre during arc exposure. In this work, the determination of the fibre temperature was based on Plank's blackbody radiation law. The radiation emitted by the optical fibre during heating due to an electric arc discharge, detected using a Cronin spectrometer, was fitted to the emission spectrum of the blackbody radiation, allowing the estimation of the temperature range attained by the fibre. A peak temperature of 1400 +/- 50 degrees C was obtained.

Abstract
We have investigated the sensitivity of arc-induced long-period gratings to changes of ambient refractive index. Two pure-silica-core fibres with different cladding diameters and a standard fibre were used in this study. For a 6 x 10(-3) change of the refractive index, a 240 pm shift of the resonant wavelength was achieved with long-period gratings written in the 125 mu m cladding diameter pure-silica-core fibre.