Caracterisation des contraintes et deformations residuelles dans les fibres optiques et composants tout-fibre

Since the late 1990's, the study of stresses and strains in optical fibers has been of growing interest. Stresses and strains in optical fibers modify the refractive index profile. Those perturbations can be desirable, for example in creating long period gratings (LPG, which enable coupling between core and cladding modes) or polarisation maintaining fibers, or they can be a nuisance by inducing defects such as polarization mode dispersion (PMD) which proves to be of critical importance for high-speed applications (∼40 Gbps). The development of efficient and accurate characterization is therefore of utmost importance in order to better understand the effects of stresses and strains. This work is aimed at describing a novel and improved measurement method based on the non-linear regression of a phase-modulated signal. Also, a more complete understanding of the different contributions to refractive index anisotropy is also achieved through signatures in the phase profile due, for example, to viscoelasticity, thermal gradients and expansion coefficient mismatch in the fiber. Several fibers have been studied in order to characterize the measurement method (offering a resolution below 10-4 radians) and observe the various signatures. The circularly symmetric fibers characterized are the standard Corning SMF-28, the photosensitive Fibercore PS1500 and PS1250 and the Nufern Erbium doped fiber. SMF-28 based fiber tapers are also characterized. Asymmetric fibers studied are the "panda" polarization maintaining fiber and a microstructured (holey) fiber from the Institut national d'optique (INO).