Diffusion coefficients of boron in vitreous silica at high temperatures

Kirchhof, J.; Unger, Sonja; Dellith, Jan; Scheffel, A.; Teichmann, C.

doi:10.1364/ome.2.000534

Cited by 10 publications

(4 citation statements)

References 23 publications

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“…1, showing the individual deposited cladding layers with a mean refractive index close to SiO2. In the core region, under the influence of the high temperature collapsing process, evaporations are supported by a high diffusion rate that takes place on the inner consolidated Ge/B doped layer under formation of GeO and BO2, leading to the well-known 'dip' in the preform center [10,11]. The negative refractive index change (Δn) in the center is caused by a boron excess in this region.…”

Section: Ge/b Co-doped Silica Preform and Fibermentioning

confidence: 99%

Multi-core optical fibers with adapted functionalities for imaging and sensing applications

Unger,

Reichert,

Aichele

et al. 2024

Optical Components and Materials XXI

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Applying the highly versatile and flexible MCVD technology at Leibniz-IPHT two new designs for optical sensing fibers were realized by co-doping of fused silica. For FBG sensing a Ge/B co-doped fiber with a mode field diameter adapted to standard single mode telecom fibers was prepared. The influence of boron on the attenuation at the inscription wavelength 1550 nm is visible. For distributed Brillouin sensing applications a preform with lateral separated germanium and aluminum doped regions and nearly step-index characteristic was fabricated by the MCVD in combination with the solution doping technique. Theoretical analysis of the acoustic properties and Brillouin spectrum have been shown, that this design is a potential candidate for strain and temperature discrimination. Because of the high temperatures during the preparation processes the radial refractive index and dopant concentration profiles of both fiber designs are influenced by diffusion.

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Section: Ge/b Co-doped Silica Preform and Fibermentioning

confidence: 99%

Multi-core optical fibers with adapted functionalities for imaging and sensing applications

Unger,

Reichert,

Aichele

et al. 2024

Optical Components and Materials XXI

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“…Dopant diffusion has been evaluated during MCVD processing of silica preforms with various dopants [5,6,8,13]. The basic concepts developed there will be applied to the fiber drawing process.…”

Section: Thermodynamical Kinetic and Geometrical Approximationsmentioning

confidence: 99%

“…In addition to thermally induced effects of dopant depletion, there also appear kinetic limitations due to dopant diffusion. Dopant diffusion has been evaluated during MCVD processing of silica preforms with various dopants [ 5 , 6 , 8 , 13 ]. The basic concepts developed there will be applied to the fiber drawing process.…”

Section: Thermodynamical Kinetic and Geometrical Approximationsmentioning

confidence: 99%

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Diffusion and Interface Effects during Preparation of All-Solid Microstructured Fibers

Kobelke¹,

Jörg²,

Wondraczek³

et al. 2014

Materials

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All-solid microstructured optical fibers (MOF) allow the realization of very flexible optical waveguide designs. They are prepared by stacking of doped silica rods or canes in complex arrangements. Typical dopants in silica matrices are germanium and phosphorus to increase the refractive index (RI), or boron and fluorine to decrease the RI. However, the direct interface contact of stacking elements often causes interrelated chemical reactions or evaporation during thermal processing. The obtained fiber structures after the final drawing step thus tend to deviate from the targeted structure risking degrading their favored optical functionality. Dopant profiles and design parameters (e.g., the RI homogeneity of the cladding) are controlled by the combination of diffusion and equilibrium conditions of evaporation reactions. We show simulation results of diffusion and thermal dissociation in germanium and fluorine doped silica rod arrangements according to the monitored geometrical disturbances in stretched canes or drawn fibers. The paper indicates geometrical limits of dopant structures in sub-µm-level depending on the dopant concentration and the thermal conditions during the drawing process. The presented results thus enable an optimized planning of the preform parameters avoiding unwanted alterations in dopant concentration profiles or in design parameters encountered during the drawing process.

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Congruent Evaporation of Borosilicate Glass Strengthening Silica Fiber

Eronyan,

Kulesh,

Tsibinogina

et al. 2024

Silicon

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The work aims to study the evaporation process of borosilicate glass used for strengthening of silica ber light guides. The composition of glass after high-temperature treatment was determined based on refractive index measurement. It was found that at temperature 2100 o C two-component SiO 2 -B 2 O 3 glass vaporizes without changing its composition at a boron oxide content of ≈ 4 mol% in both oxygen and nitrogen atmospheres. The IR absorption spectra of borosilicate glass indicate the absence of boroxol rings of B 2 O 3 , which can explain the low partial pressure of its vapors compared to the ideal melt state. It is experimentally shown that the content of only 1 mol % B 2 O 3 in the outer cladding of silica ber increases its strength by 10% when the drawing temperature is reduced to 1900°C. Such a small addition of boron oxide to silica glass decreases its viscosity, ensuring the occurrence of compressive stresses in the borosilicate cladding.

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Diffusion coefficients of boron in vitreous silica at high temperatures

Cited by 10 publications

References 23 publications

Multi-core optical fibers with adapted functionalities for imaging and sensing applications

Multi-core optical fibers with adapted functionalities for imaging and sensing applications

Diffusion and Interface Effects during Preparation of All-Solid Microstructured Fibers

Congruent Evaporation of Borosilicate Glass Strengthening Silica Fiber

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