Cinética inicial de formación de rejillas de Bragg en fibras ópticas estándar

Abstract

Results on experimental study on kinetics of fiber Bragg gratings formation in the standard telecom optical fiber SMF-28 at initial stage of irradiation are presented. For low fluence per pulse, it was found that the fast formation of color centers Ge(1) is a dominant mechanism of the refractive index change at initial stage for accumulated fluence of below 0.02 J/cm$^2$ at the wavelength of 266 nm. At low fluence per pulse, the induced change of the refractive index does not depend on UV light intensity and saturates at a level of $ \sim 2 \times 10^{-6} $. Dominance of the Ge(1) color center mechanism in the FBG formation at the initial stage makes possible a cost-effective recording of large arrays of weak FBGs for sensors utilizing lasers of low energy per pulse.