Abstract
An all-optical fibre referencing scheme for intensity based sensors which uses two identical fibre Bragg gratings is described. It provides a general and simple miniature sensor design with referencing effectiveness against system power fluctuations. The concept is demonstrated for a reflective-type displacement sensing cavity, and its potential for simultaneous measurand and temperature evaluation is evaluated.

Abstract
A low coherence interferometric system with large tracking range and self-initialization to be used for remote signal processing of fiber optic accelerometers is investigated. The tracking range of the low coherence system is 1.1 mm at low frequency. Phase resolution better than 1 mrad/ square-root Hz at frequencies below 600 Hz is obtained, with a dynamic range of almost-equal-to 90 dB. Data are presented which show that if the system were used to process the output from a compliant cylinder-type accelerometer, resolutions of approximately 10(-7) g/ square-root Hz could be achieved.

Abstract
In this article, approaches reported in the literature for multi-parameter measurement relying on fiber grating technology are reviewed. Due to its importance, the particular case of temperature/strain simultaneous measurement is addressed in further detail, as well as the techniques and sensing heads for temperature-independent strain measurement. Specific criteria are also proposed for sensing head classification in the context of multi-parameter measurement.

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 and temperature. It can also be used to measure other parameters such as acceleration, angle and acoustic pressure.

Abstract
In this work two sensing heads based on fibre Bragg grating structures are demonstrated, one for temperature independent measurement of strain and the other for simultaneous measurement of these two parameters. The first one relies on a single Bragg grating inscription in a microstructured optical fibre, resulting for two input orthogonal polarizations in two distinct resonance peaks with similar temperature sensitivities and different strain sensitivities. In the second structure two gratings were considered, one written in the same microstructured fibre and the other on a standard SMF fibre. Considerably different strain and temperature sensitivities were obtained for these two gratings, enabling simultaneous temperature and strain measurement with resolutions of +/- 1.5 degrees C and +/- 10.7 mu epsilon over a measurement range of 100 degrees C and 2000 mu epsilon, respectively.

Abstract
In this work, two sensing heads based on the fibre Bragg gratings written in fused biconical fibre taper for simultaneous measurement of temperature and strain are proposed. In the first configuration a comparison between a uniform Bragg grating and a grating written on a tapered fibre section, resulting in a chirp grating, is evaluated. The second sensing head consists of two gratings written in two different regions of the taper section. This fibre taper has a different geometry in each conical section, achieved by stretching the fibre at different velocities during the fabrication process. These two configurations are based on the different strain and similar temperature sensitivities of the Bragg gratings used to discriminate the two physical parameters. The performances are assessed and compared. The second structure presents good performance and more sensitivity, compared to the first sensing head.