Crystalline and amorphous phases of GeO2 in VAD silica–germania soot preform

Sekiya, Edson Haruhico; Torikai, Delson; Gusken, Edmilton; Ogata, Daniela Y; Cuevas, Raúl; Suzuki, Carlos Kenichi

doi:10.1016/s0022-3093(00)00131-9

Cited by 9 publications

(7 citation statements)

References 7 publications

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“…Recent studies of silica soot particles (SiO 2 ) in MCVD have found them to be invariably amorphous [7]. Several studies of the VAD process [8][9][10][11][12][13][14] have reported that under certain conditions some of the GeO 2 soot particles formed are crystalline. Crystalline GeO 2 has never been reported in MCVD.…”

Section: Introductionmentioning

confidence: 99%

Germania nanocrystals in Modified Chemical Vapour Deposition

Cheung

McNamara

Barton

et al. 2008

Journal of Non-Crystalline Solids

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Section: Introductionmentioning

confidence: 99%

Germania nanocrystals in Modified Chemical Vapour Deposition

Cheung

McNamara

Barton

et al. 2008

Journal of Non-Crystalline Solids

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“…7 shows the germanium doping profiles from the lower and upper extremity and the center of the preform. The higher GeO 2 concentration of the outer diameter region in comparison to the center of the preform is due to the deposition of the crystalline phase of GeO 2 induced by a lower temperature of deposition [19], [20]. Dehydration with Cl 2 gas was not considered in these preforms, which explains the effect of noelimination of the GeO 2 crystalline phase [21].…”

Section: Correlation Between Preform Bottom Profile and Germaniumentioning

confidence: 99%

Correlation study between VAD preform deposition surface and Germanium doping profiles

Santos

Ono

Gusken

et al. 2006

J. Lightwave Technol.

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The refractive index profile of germanium doped preforms for optical fibers is determined by the radial distribution of germanium concentration. Knowing that there is a correlation between the germanium doping profile and the deposition surface profile of vapor-phase axial deposition (VAD) preforms, the study of this correlation has been carried out in order to estimate, indirectly, the refractive index profile of VAD preforms for optical fibers during the deposition stage. This correlation was studied through the parameterization of the preform deposition surface using two parameters: the power law index profile that best fits the preform bottom profile (α) and the axial distance from the bottom tip to a reference height (h). A range of values of these parameters to produce VAD preforms with standard and special doping profiles has been presented. Preforms with triangular index profile can be fabricated with α and h values of about 2.0 and 5.0 mm, respectively, and preforms with parabolic index profiles can be produced with α and h values of about 2.0 and 4.0 mm, respectively.

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“…During the soot deposition, germania may be deposited as amorphous and/or crystalline phases according to the preform surface temperature that is established by many processing parameters. 10 The amorphous phase, which is formed in higher temperature regions, is very stable in the dehydration. On the other hand, the crystalline hexagonal phase, which is formed in lower temperature regions, is unstable for chlorination reaction in the dehydration process.…”

Section: Preform Fabrication and Characterizationmentioning

confidence: 99%

“…16 Previous experiments conducted in our laboratory showed that there are optimized processing conditions that maintain the germanium doping profile characteristics of unsintered soot preform related to the doping profile in the sintered preform. 10,17 To determine the radial distribution of the germanium doping profile a Rigaku RIX3100 x-ray fluorescence spectrometer was used. Silica-germania samples were prepared by slicing consolidated preforms along their axes.…”

Section: Preform Fabrication and Characterizationmentioning

confidence: 99%

“…Many factors, such as H 2 /O 2 ratio in the flame, SiCl 4 / GeCl 4 reactant ratio, burner geometry, radial and axial distributions of deposition temperature, and soot preform geometric shape ͑diameter and bottom shape͒, among others, are involved. [8][9][10] Longperiod fluctuations of these parameters cause refractive index profile variations in the axial direction, as several hours are needed to fabricate a long soot preform.…”

Section: Introductionmentioning

confidence: 99%

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Automation for monitoring of the refractive index profile of vapor-phase-deposited soot preforms for optical fiber

Santos

Ono

Suzuki

2006

Review of Scientific Instruments

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The vapor-phase axial deposition process is currently one of the most advantageous methods to produce preforms for optical fibers, due to its high efficiency and reduced production cost. However, this method has great difficulty in determining the refractive index profile, since it is influenced by too many process parameters. In this work, an automation system to determine the refractive index profile by monitoring the preform deposition surface profile during the soot preform deposition stage is presented. Based on a previous study that showed a strong correlation between these two profiles, an automation system was developed in LABVIEW to monitor the deposition surface profile during the preform deposition stage in order to estimate the preform germanium doping profile and refractive index profile, as well as a theoretical study to develop this system in order to minimize the performance impairment. As a result, not only preforms with a predetermined index profile were produced but also a reduction in production cost was obtained by decreasing the number of preform rejects.

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Crystalline and amorphous phases of GeO2 in VAD silica–germania soot preform

Cited by 9 publications

References 7 publications

Germania nanocrystals in Modified Chemical Vapour Deposition

Germania nanocrystals in Modified Chemical Vapour Deposition

Correlation study between VAD preform deposition surface and Germanium doping profiles

Automation for monitoring of the refractive index profile of vapor-phase-deposited soot preforms for optical fiber

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