Abstract
A spatial optical filter based on splice misalignment between optical fibers with different cladding dimensions is proposed for gas refractometry. The sensing head is formed by a 2 mm-long optical fiber with 50 mu m diameter spliced with a strong misalignment between two single mode fibers (SMF28) and interrogated in transmission. This fiber structure causes a Fabry-Perot-behavior along the reduced-size fiber giving at its output end a well defined spatial filtering selectivity. Depending on the misalignment position of the lead-out SMF28, it is possible to obtain two different spectral responses, namely, bandpass or band-rejection filters. It is shown that this filter device is highly sensitive to refractive index changes on a nitrogen (N-2) environment by means of the gas pressure variation. A maximum sensitivity of -1390 nm/RIU for the bandpass filter was achieved.

Abstract
Tapering single mode-multimode-single mode structures to enhance sensitivity is proposed and experimentally demonstrated. 50 mm-long coreless MMF sections are spliced between SMFs and tapered. They are characterized in strain and an increase in strain sensitivity is obtained with taper diameter reduction. Sensitivities as high as -23.69 pm/mu epsilon for the 15 mu m taper are attained. A combination of an untapered and tapered SMS is proposed as a sensing system for the simultaneous measurement of strain and temperature.

Abstract
In this contribution we propose an alternative approach to the traditionally used apodized chirped fiber Bragg gratings for dispersion compensation applications. The unchirped grating proposed has a refractive index perturbation with varying negative mean, acting simultaneously as optical filter demultiplexer and efficient group velocity dispersion compensator in wavelength division multiplexing systems.

Abstract
Fiber Bragg Gratings (FBG's) are nowadays widely used in various fields, including telecommunications. Since emergence, this component has found many applications due to its properties, versatility and variety of controllable parameters that can shape in various manners its spectral properties. These devices have the advantage of being built of fiber and they are widely used in mono and multichannel networks.

Abstract
In this paper, we report experimental results on the frequency control of an optical oscillator based on a single-cavity DFB-MQW laser and a fiber loop reflector. Self-pulsation frequency can be controlled by changing the step amplitude of the laser bias current.

Abstract
In this research programme methodologies to improve the accuracy in the results measured with embedded fibre Bragg gratings (FBG) sensors were studied and implemented in order to produce a composite overwrapped pressure vessel (COPV) prototype that incorporate a non-destructive sensing technologies. Using a carbon/epoxy prepreg system, test specimens were manufactured with longitudinally embedded FBG sensors. The combined behaviour of the sensors and the host material was characterized and a calibration rule (correction factor) was determined for the chosen material. The consistency of the results with both theoretical and empirical assumptions suggests that the proposed method is applicable to a wide range of FBG sensors and host materials. In this paper, the experimental setup and procedure used to assess to the calibration rule is addressed and further detailed.