Abstract:
The specification describes a VAD method for producing optical fiber preforms by depositing soot onto a solid core rod. The solid core rod preferably has a uniform composition, doped or undoped, suitable for the center core region of the preform. The primary cladding layer, and additional cladding layers if desired, are produced by depositing soot on the center core rod. The surface of the center core rod is treated with an etchant torch that traverses the center core rod in front of the soot deposition torch. This produces a clean interface between the core and primary cladding. This soot-on-center-core-rod method allows the production of sharp index profiles by reducing the diffusion of dopants into and out of the center core portion of the preform that occurs in soot-on-soot processes.
Abstract:
A modified synthetic silica powder is produced by heating in vacuum an amorphous synthetic silica powder produced by a sol-gel process, and then cooling the heated silica powder in an atmosphere containing helium. When the modified synthetic silica powder is fused and vitrified in a process of crucible production, the resulting quartz glass crucible contains hardly any bubbles.
Abstract:
A method for manufacturing a preform, which is a base material of an optical fiber, comprising: forming porous-glass-base-material by accumulating glass particles; dehydrating the porous-glass-base-material by heating the porous-glass-base-material in an atmosphere of gas that contains chlorine; heating the porous-glass-base-material dehydrated by the dehydrating with a first heating temperature in an atmosphere of a first inert gas; and vitrifying the porous-glass-base-material by heating the porous-glass-base-material with a second heating temperature in an atmosphere of second inert gas.
Abstract:
A method for forming a fused silica glass includes delivering a silica precursor to a burner and passing the silica precursor through the flame of the burner to form silica particles, depositing the silica particles on a planar surface to form a flat, porous preform, dehydrating the porous preform, and consolidating the porous preform into a flat, dense glass.
Abstract:
A refractory dielectric body is heated with a plasma fireball at conditions which do not result in substantial removal of a surface portion of the body, yet which are sufficient to reduce both surface and bulk impurities. Typically, the body is treated with the plasma in the absence of simultaneous deposition of material onto the body. Advantageously, an isothermal, oxygen or oxygen-containing plasma is utilized. The invention is useful for reducing chlorine impurities by at least about 30% to a depth of at least about 10 .mu.m, with accompanying reduction of hydroxyl impurities. The invention thus provides a useful method for reducing the concentration of impurities that contribute to imperfections during the process of drawing fiber from an optical fiber preform, without requiring substantial removal of the surface of the preform.
Abstract:
A quartz glass crucible for use in a process for pulling a single crystal silicon and having an outer layer and an inner layer. The outer layer contains less than 0.3 ppm each of Na, K and Li and more thant 5 ppm of Al. The outer layer further contains bubbles to present an opaque appearance. The inner layer is made by melting powders of high purity non-crystalline synthetic silica and contains less then 200 ppm of OH group. There is also disclosed a method for producing the crucible.
Abstract:
Reproducible doped optical fiber preforms having a predetermined dopant concentration level are fabricated by inserting a doped filament into a completed preform prior to consolidation and final collapse so that the filament and dopant materials are centrally located in the core region upon formation of the preform. Doped fiber is drawn from the doped preform using standard fiber drawing techniques.
Abstract:
Light-conducting optical fibers in which both the core and sheath consist essentially of quartz glass are provided by encasing a relatively anhydrous quartz glass core with a quartz glass sheath having a sufficiently high water content to lower the refractive index thereof. The fibers are ideally suited for the transmission of ultraviolet light with maximum efficiency.
Abstract:
A fiber optic construction is described combining low OH (preferably 0/d ratios to provide extended life expectancy fiber optics for use in high-temperature environments.