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Titre de la technologie / Technology Title
Procédé de fabrication de réseaux de Bragg par laser femtoseconde dans les fibres optiques dopées aux terres rares
The present invention is a photo-engraving process enabling the fabrication of low background loss fiber Bragg gratings in rare-earth doped fibers. The process uses short wavelength high intensity femtosecond pulses and a phase mask to focalise the light in fiber core thus producing permanent refraction index changes. However, this photo-engraving process also induces strong background loss in the fiber that are completely removed by locally heating the exposed fiber. This process works for any rare-earth doped fibers but it is especially relevant for Ytterbium doped fibers, which are the gain medium of choice for high power lasers emitting in the 0.9 to 1.2 micron range.