Abstract:
A method of forming an alkali metal oxide-doped optical fiber by diffusing an alkali metal into a surface of a glass article is disclosed. The silica glass article may be in the form of a tube or a rod, or a collection of tubes or rods. The silica glass article containing the alkali metal, and impurities that may have been unintentionally diffused into the glass article, is etched to a depth sufficient to remove the impurities. The silica glass article may be further processed to form a complete optical fiber preform. The preform, when drawn into an optical fiber, exhibits a low attenuation.
Abstract:
Applicants have discovered the existence of loss peaks in optical fiber transmission systems using wavelengths in the E-band and the L-band. Specifically, they have discovered the existence of narrow loss peaks at 1440 nm, 1583 nm and 1614 nm. Because the peaks are relatively narrow, they cannot be easily removed by conventional gain equalizers in long haul transmission systems, and although the peaks are relatively small, they can nonetheless cause transmission channels to drop out in amplified DWDM transmission systems. Applicants have further discovered that these loss peaks are due to carbon contamination of the transmission fiber. Thus optical fibers should be fabricated essentially free of carbon contamination. This means eliminating carbon-containing reagents in preform and tube-making processes.
Abstract:
An object of the present invention is to overcome the problems of the prior art technique, and to provide a heat treatment method as well as a heat treatment apparatus capable of heat treating, with higher efficiency, a synthetic quartz glass for optical use having higher homogeneity and higher purity. Another object of the present invention is to provide and a synthetic quartz glass for optical use. The problems above are solved by, in a method for heat treating a flat cylindrical synthetic quartz glass body provided as the object to be heat treated in a heating furnace, a method for heat treating a synthetic quartz glass for optical use comprising preparing a vessel made of quartz glass and having a flat cylindrical space for setting therein the object synthetic quartz glass body, placing two or more object synthetic quartz glass bodies into the vessel in parallel with each other, filling the space with SiO2 powder, setting the vessel inside the heating furnace with its lid closed, and applying the heat treatment to the vessel.
Abstract:
An article of relatively pure silica, and a furnace and method of producing the article. The article is produced by collecting molten silica particles in a refractory furnace in which at least a portion of the refractory has been exposed to a halogen-containing gas to react with contaminating metal ions in the refractory.
Abstract:
A method for preparing high-purity, bulk fused silica includes supplying silane gas, a gaseous fuel, and oxygen gas to a combustion burner. Silica particles are formed by passing the silane gas into a flame formed by the combustion reaction of the gaseous fuel with the oxygen gas while maintaining the ratio of the flow rate of the gaseous fuel to the flow rate of the silane gas no less than twelve and the ratio of the flow rate of the gaseous fuel to the flow rate of the oxygen gas no less than three. The silica particles formed are immediately deposited onto a hot bait to form a boule.
Abstract:
A method for producing a high purity synthetic quartz powder, characterized by using a tetramethoxysilane having a trimethoxymethylsilane content of at most 0.3 wt %, and converting it to a synthetic quartz by a sol-gel method.
Abstract:
In a quartz glass crucible obtained by heating and fusing a rotating layer (3) charged with a powder of silicon dioxide, impurity elements are controlled so that copper, chromium, and nickel each amount to 0.5 ppb or less, iron amounts to 120 ppb or less, and sodium amounts to 20 ppb or less. The silicon dioxide powder is supplied to a rotatable mold (1) having an open top, thereby forming a layer (3) charged with silicon dioxide along the inner peripheral wall of the mold. The layer (3) is internally heated and fused while covering the open top with a lid (5) having two or more holes (6,7), and the mold (1) is ventilated to discharge the high temperature gases through the holes (6,7).
Abstract:
A vertical heat treatment apparatus that includes a reaction tube for wafers to be loaded into from below and a heating unit surrounding the reaction vessel, or a single wafer heat treatment apparatus having a holder which provides a mount for wafers being loaded one by one into a reaction tube for heat treatment. The reaction tube has a structure of, e.g., two layers with a first layer of synthetic quartz glass made from a silicon compound, such as silicon tetrachloride, as a raw material. The first layer represents a surface that comes in contact with a heat treatment atmosphere. The second layer is of molten quartz glass made from quartz as a raw material and is external to the first layer. Synthetic quartz glass contains such traces of metals that scattered amounts of metals released into a heat treatment atmosphere due to exposure of the reaction tube to high temperatures is substantially zero. Furthermore, synthetic quartz glass and molten quartz glass are laid on each other, which improves heat resistance of the reaction tube. Thus, in conducting oxidation, diffusion, and other heat treatments on objects to be treated, e.g., semiconductor wafers, contamination of the objects with impurities can be minimized.
Abstract:
Pure transparent quartz glass is provided by molding powdery amorphous silica into an article, converting the molded powdery amorphous silica into crystalline silica of high-temperature type cristobalite structure, and then fusing the crystalline silica, the quartz glass containing impurities respectively at a content of not higher than 1 ppm, and an OH group at a content of not higher than 20 ppm, and having a viscosity of 10.sup.12.0 poise or more at 1200.degree. C. The quartz glass is transparent and has high purity, and is excellent in high temperature viscosity characteristics. The quartz glass can be produced at a low cost.
Abstract:
A synthetic silica glass article made by hydrolyzing an alkoxysilane and thermally sintering the resulting silica; this synthetic silica glass article has a viscosity of not lower than 10.sup.10 poise at 1400.degree. C., and contains, as metallic impurities, less than 1 ppm of Al, less than 0.2 ppm of Fe, less than 0.2 ppm of Na, less than 0.2 ppm of K, less than 0.01 ppm of Li, less than 0.2 ppm of Ca, less than 0.02 ppm of Ti, less than 0.01 ppm of B, less than 0.01 ppm of P, less than 0.01 ppm of As.