Abstract
In this paper, it is presented a brief review of the sensing applications using photonic crystal fibres. Since the first publication, several authors have studied their properties and possible applications in engineering. Due to their geometry, the great potential in optical sensing is in bio and gas sensing. Recently, with the possibility of inscribing Bragg grating structures on these fibres, it is possible to use them for other applications. Finally, this paper reviews the recent works with different types of photonic crystal fibres for interferometry.

Abstract
This paper presents some aspects of the production, characterization and implementation of fibre Bragg grating as a key element for selective filtering in optical communications. Theory, fabrications and applications of the Fibre Bragg grating for a specific tuneable optical add-drop multiplexer (OADM) are presented. The OADM performance on a 2.48832 Gbit/s dense wavelength division multiplexing optical communications system with 95 km is reported. The power penalty for the removed channels was less than 0.1 dB. We obtain good agreement between the FBG behaviour the OADM performance with the numerical simulations results. Copyright SBMO.

Abstract
Fiber Bragg grating (FBG) written in normal and reduced diameter high birefringence (HiBi) optical fibers have been studied. Chemical etching is used to reduce the fiber diameter while the optical properties of the FBG spectrum are measured. The obtained results agree qualitatively with the stress enhanced chemical etching. They also permit to determine the birefringence of the fiber as a function of the diameter. Optical characterization of the FBG under transversal strain and temperature is performed. The obtained results permit the simultaneous measurement of those parameters with a HiBi FBG sensor.

Abstract
An experimental set-up configuration, which allows the self-pulsation frequency of an optical oscillator to be modified by simply adjusting the bias current between 25 and 100 mA, is presented. For lower currents, the self-pulsation frequency is near 6 GHz and the device is stable. For higher currents, the self-pulsation frequency increases to near 11 GHz.

Abstract
This paper reports a technical assessment of an all-optical 4×10 Gbps clock extraction technique in the context of fiber optic digital communication systems. The technique consists in putting a 1320 nm semiconductor laser in a self pulsating mode through injection locking to a CW source. The pulsations are triggered by a fast drive current step. The useful self pulsation region has been explored after extensive simulation providing a valuable knowledge for on-going experiments. Actual synchronization with optical data stream was observed both considering all ones and pseudo-random sequences. Phase sustaining of the clock over moderate-length sequences of zeros was noticed as the most encouraging result of this work.

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.