Abstract
This study seeks the development of adaptive composites capable to monitor and actively damp vibrations. In the proposed material, vibrations measurements are performed by an embedded low finesse optical fibre extrinsic Fabry-Perot interferometer, while active damping will be performed by embedded piezoelectric ceramics. This paper focuses on the development of the monitoring procedure. The proposed interrogation procedure for the low finesse optical fibre extrinsic Fabry-Perot interferometer was successfully used to monitor the composite plate when submitted to four-point bending dynamic tests at different frequencies. The embedding of both sensing and actuating components in carbon-fibre reinforced composite laminates is also presented. In the case of the actuator, the efficiency of the embedding process was merely analysed from the capability of the piezoelectric ceramic to monitor dynamic strain of the composite using the PZT piezoelectric inverse effect.

Abstract
A highly-birefringent photonic bandgap Bragg fiber loop mirror sensor is proposed. Thanks to the Bragg fiber geometry, one can observe the group birefringence and the bandgap fiber in the transfer function. The sensing head presented different sensitivities for strain and temperature measurements. Using the matrix method, both the physical parameters can be discriminated. It is important to highlight that this Bragg fiber presents sensitivity to temperature of similar to 5.75 nm/degrees C, for the group birefringence measurand.

Abstract
We experimentally studied several sensing characteristics of a birefringent microstructured polymer optical fiber. The fiber exhibits a birefringence of the order 2x10(-5) at 1.3 mu m because of two small holes adjacent to the core. In this fiber, we measured spectral dependence of phase and group modal birefringence, bending losses, polarimetric sensitivity to strain and temperature. The sensitivity to strain was also examined for intermodal interference observed in the spectral range below 0.8 mu m. Finally, we showed that the material transmission windows shift as function of the applied strain. This shift has an exponential character and saturates for greater strain.

Abstract
A highly birefringent photonic bandgap Bragg fiber loop mirror configuration for simultaneous measurement of strain and temperature is proposed. The group birefringence and the sharp loss peaks are observable in the spectral response. Because the sensing head presents different sensitivities for strain and temperature measurands, these physical parameters can be discriminated by using the matrix method. It should be noted that this Bragg fiber presents high sensitivity to temperature, of similar to 5.75 nm/degrees C, due to the group birefringence variation. The rms deviations obtained are +/- 19.32 mu e and +/- 0.5 degrees C, for strain and temperature measurements, respectively. (C) 2011 Optical Society of America

Abstract
In this work, a laser sensor is described that uses the multipath interference produced inside a ring cavity to measure the power loss induced by a moving taper intensity sensor. The laser is created due to the virtual distributed mirror formed by the Rayleigh scattering produced in a dispersion compensating fiber when pumped by a Raman laser. Two laser peaks were formed, one of them is obtained by the Raman gain (1555 nm) inside the ring and the second is created by the combination of the Raman gain and the Rayleigh scattering (1565 nm). A taper sensor is used as displacement sensor and when the losses is applied in the taper the second laser peak is reduced and the first peak is maintained constant and can be used as reference level.

Abstract
The index-guiding PCF basic structure is a solid core surrounded by a microstructured cladding. Owing to the presence of air holes, the effective refractive index of the cladding is below that of the core and the light is guided along the core by the principle of total internal reflection. Several authors have presented different geometries for this type of fibre and one of them is the suspended-core structure, where relatively large holes surround the fibre core that looks suspended along the fibre axis by small width silica walls. The chapter is divided in two parts. The first is about the fabrication of suspended core fibre and the second part is about the main applications of this type of fibres as interferometers.