Abstract
In this research programme, methodologies for structural health monitoring (SHM) of composite overwrapped pressure vessels (COPV) were addressed. This works fit in the development of a COPV laboratorial prototype incorporating non-destructive sensing technologies, in order to detect and identify critical aspects that can occur during operation, aiming to reduce possible unwanted and unpredicted failures. Fibre Bragg grating (FBG) optical sensors and polyvinylidene Fluoride (PVDF) polymeric piezoelectric were the selected sensing technologies. These sensors were embedded in the liner-composite interface during its manufacturing and monitored the prototype while being tested under cyclic internal pressure loading. The data collected from the different sensors type were compared. The Analysis of the data, together with the assessment to the suitability of the two sensing technologies in SHM applications are discussed.

Abstract
In this work, a fiber loop mirror for the simultaneous measurement of strain and temperature is presented. The loop mirror contains a section of a small core microstructured fiber characterized for strain and temperature sensing. Due to the small core geometry and using a small section length, the structure presents high birefringence and also intermodal interference. The spectral response of this configuration shows the presence of three interferometers. One of them corresponds to the interference of light that propagates in the fast and slow axes (group birefringence) and the others are associated with the interference of light in the two lowest order spatial modes in each of the fiber eigenaxis. These interferometers present distinct sensitivities to strain and temperature for different wavelengths.

Abstract
Fiber Bragg grating (FBG) arrays in pure silica four-leaf-clover-shaped suspended core fibers were inscribed with two-beam interference and a deep UV femtosecond laser source. The target fibers are pure silica and do not contain any dopants, nor were they treated with hydrogen before grating inscription. The inscription method is appropriate to measure the effective mode field index of the fiber and allows confinement factors of the guided modes to be derived. Applications of such FBGs can be expected especially for fiber sensing.

Abstract
This work presents a method to tune the sensitivity of the sensor in a highly birefringent erbium-doped fiber loop mirror (FLM) when it is pumped. This concept was used for simultaneous measurement of strain and temperature. The FLM is sequentially pumped and unpumped by a high pump laser at 980 nm to change the erbium-doped fiber properties. The sensing head changes its sensitivity when subjected to strain and/or temperature variations due to thermal effects originated by the pump laser.

Abstract
An interferometric setup for measuring Polarization Mode Dispersion (PMD) setup was tested. Using a low-coherence technique with a Michelson interferometer, it was possible to measure values of PMD from detected Differential Group Delay (DGD) values in two reels. The low-coherence source bounds the minimum value of DGD detected to 0.13 ps, leading to a minimum value detected around 0.14 ps. The mean value of PMD measured over a period of several days for one reel was 0.0405 +/- 0.0007 ps/km(1/2), and 0.0463 +/- 0.0044 ps/km(1/2) for the other. Stochastic and random behavior of PMD was observed.

Abstract
A polarization mode dispersion (PMD) emulator and compensator device is proposed. The PMD device is obtained using a Hi-Bi Fibre Bragg Grating (Hi-Bi FBG) and a stress induced bireffingence in a uniform FBG. This birefringence is achieved by applying transverse and uniform distributed force on the uniform fibre Bragg grating creating a tuneable differential group delay (DGD). Maximum and minimum slopes of 377 ps/nm and 0 ps/mn in the DGD is obtained for the PMD emulator/compensator device, respectively.