Characterization of soot from multimode vapor-phase axial deposition (VAD) optical fiber performs

Composition, degree of crystallinity, particle size, and soot packing density of a multimode VAD porous sootform fabricated under optimum standard processing conditions were evaluated with 1-mm radial resolution using several analytical methods. The methods include inductively coupled plasma emission spectroscopy, the X-ray diffraction powder method, a simple mass/volume calculation, and transmission electron microscopy. Within individual particulate, the GeO/sub 2/ and SiO/sub 2/ appear as separate phases as opposed to a compound glass. The degree of fusion observed in the particle aggregates indicates that the soot packing density profile is established by a surface sintering process governed predominantly by the deposition surface temperature distribution. This study has general significance in clarifying the behavior of dopants during various processing steps associated with VAD and other soot processes, including the MVCD (modified chemical vapor deposition) and OVD (outside vapor-phase deposition) lightguide processes.<
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