Annealing properties of fiber Bragg grating UV-inscribed in boron-germanium codoped fiber.

ABSTRACT

In this work, we mainly focus on the investigation of the feasibility of production of high-temperature stable fiber Bragg grating (FBG) based on reduplicative alternate annealing and hydrogen loading. The experimental results also can demonstrate the significance of the presence of hydrogen to the thermal regeneration of FBGs. The gratings are characterized and variations are compared after each stage, including UV fabrication, annealing, and reduplicative hydrogen-preloaded annealing. In different stages, the spectral and annealing responses of FBG are, respectively, investigated, as temperature increases, the Bragg wavelength consistently shifts to longer wavelengths; nevertheless, the reflection variations are distinctly discrepant. After reduplicative alternate annealing and hydrogen loading, the thermal stability is tremendously improved, and a reborn, stable grating is formed.