Density and concentration fluctuations in SiO2–GeO2 optical fiber glass investigated by small angle x-ray scattering

Abstract

Density and concentration fluctuations have been investigated in a 3mol% GeO2 doped silica glass as a function of the fictive temperature (the temperature at which the structure of the supercooled liquid has been frozen-in to form the glass) by small angle x-ray scattering measurements. The fluctuations increase in a way is quite similar to that observed for pure silica glass as a result of density fluctuation fictive temperature dependence. Fluctuations have also been studied in glasses containing different amounts of GeO2 up to 21mol% GeO2. The fluctuations are shown to increase very strongly with germanium amount as a result of strong concentration fluctuation increase. This observation is in agreement with already observed excess losses in light scattering measurements.

Evolution of Photo-induced defects in Ge-doped fiber/preform: influence of the drawing

“…By using the Eq. (7) and 8 we find that the generation probability c (~10 24 kGy 1 cm 3 ) is always 5 orders of magnitude lower than the destruction probability b (~10 19 kGy 1 cm 3 ). These values are useful to explain the experimental fact that the radiation-induced concentrations of Ge(1) and Ge(2) are low even if the concentrations of their precursors are high.…”

“…Similarly from the fits of the Ge(2) kinetics we obtain sat values of (8.6 ± 2.2) × 10 17 defects/cm 3 and (4.9 ± 1.7) × 10 17 defects/cm 3 and Dsat values of (1.4 ± 0.4) × 10 1 kGy 1 and (0.40 ± 0.14) × 10 1 kGy 1 for the fiber FGe and the preform PGe, respectively. It is important to note that in zone 4 the GLPC content is the largest and is one order of magnitude larger than the maximum Ge(2) induced concentration, preventing to evidence the related decrease of the GLPC using the emission or OA spectra.…”

“…From the fits of the Ge(1) kinetics, we obtain sat values of (6.3 ± 1.6) × 10 17 defects/cm 3 , (3.2 ± 1.1) × 10 17 defects/cm 3 and Dsat values of (1.8 ± 0.5) × 10 1 kGy 1 and (0.40 ± 0.14) × 10 1 kGy 1 for the fiber FGe and the preform PGe, respectively. Similarly from the fits of the Ge(2) kinetics we obtain sat values of (8.6 ± 2.2) × 10 17 defects/cm 3 and (4.9 ± 1.7) × 10 17 defects/cm 3 and Dsat values of (1.4 ± 0.4) × 10 1 kGy 1 and (0.40 ± 0.14) × 10 1 kGy 1 for the fiber FGe and the preform PGe, respectively.…”

“…Ge doped silica has been studied since many years because this material is used for the realization of several optical devices [1][2][3][4]. Historically, Ge doping was used for the production of the fibers because the presence of Ge increases the refractive index of silica [5].…”

Formation of optically active oxygen deficient centers in Ge-doped SiO2 by γ- and β-ray irradiation

“…In telecommunication many devices [1], and some complex signal processing operations can be performed by optical fibers in which a spatial modulation of the refractive index has been induced [4]. Moreover, they are used to realize sensors, multiplexers [1,5,6], or optical devices that need selectivity of wavelengths [7]. The fibers are also used in other technologic fields, for example fibers co-doped with aluminum and germanium are a promising gain medium for high power lasers [8].…”