Title :
Study of hydrogen diffusion in boron/germanium codoped optical fiber
Author :
Swart, Pieter L. ; Chtcherbakov, Anatoli A.
Author_Institution :
Centre for Opt. Commun. & Sensors, Rand Afrikaans Univ., Johannesburg, South Africa
fDate :
11/1/2002 12:00:00 AM
Abstract :
Presents a novel technique for studying the dynamics of hydrogen diffusion in optical fiber. It shows that the hydrogen contributes directly to the effective refractive index of the fiber by its dielectric susceptibility. It provides a simple theory that relates the refractive index change to the total hydrogen concentration in the fiber core. It also deduces that there is a small contribution of less than 5% to the refractive index through the photoelastic effect. A low-finesse fiber Bragg grating Fabry-Perot interferometer allows the determination of the evolution of the hydrogen concentration in situ. The experimental results obtained for isothermal and isobaric diffusion between 45°C and 90°C yielded values for the parameters of Arrhenius-type expressions for the diffusivity, permeability, and solubility of hydrogen in germanium/boron codoped single-mode fiber. In addition, least squares curve-fits for outdiffusion yielded the gas-phase mass-transfer coefficient as a function of temperature.
Keywords :
Bragg gratings; borosilicate glasses; diffusion; germanate glasses; hydrogen; optical fibres; optical susceptibility; permeability; photoelasticity; refractive index; silicon compounds; solubility; 45 degC; 90 degC; Arrhenius-type expressions; SiO2-GeO2-B2O3:H2; SiO2:Ge,B,H2; amorphous SiO2; boron/germanium codoped optical fiber; dielectric susceptibility; diffusivity; effective refractive index; fiber core; gas-phase mass-transfer coefficient; hydrogen diffusion dynamics; isobaric diffusion; isothermal diffusion; least squares curve-fits; low-finesse fiber Bragg grating Fabry-Perot interferometer; molecular hydrogen; outdiffusion; permeability; photoelastic effect; refractive index; refractive index change; solubility; temperature dependence; total hydrogen concentration; Boron; Dielectrics; Fabry-Perot interferometers; Germanium; Hydrogen; Isothermal processes; Optical fiber theory; Optical fibers; Photoelasticity; Refractive index;
Journal_Title :
Lightwave Technology, Journal of
DOI :
10.1109/JLT.2002.806325