A method for preparing quartz glass with low content of hydroxyl and high purity, includes providing silica powders including hydroxyl groups. The silica powders are dehydroxylated, which includes drying the silica powders at a first temperature, heating the silica powders up to a second temperature and introducing a first oxidizing gas including halogen gas, thereby obtaining first dehydroxylated powders, and heating the first dehydroxylated powders up to a third temperature and introducing a second oxidizing gas including oxygen or ozone, thereby obtaining second dehydroxylated powders. The second dehydroxylated powders are heated up to a fourth temperature to obtain a vitrified body. The vitrified body is cooled to obtain the quartz glass with low content of hydroxyl and high purity. The quartz glass prepared by the above method has low content of hydroxyl and high purity. A quartz glass with low content of hydroxyl and high purity is also provided.

A method for preparing quartz glass with low content of hydroxyl and high purity, includes providing silica powders including hydroxyl groups. The silica powders are dehydroxylated, which includes drying the silica powders at a first temperature, heating the silica powders up to a second temperature and introducing a first oxidizing gas including halogen gas, thereby obtaining first dehydroxylated powders, and heating the first dehydroxylated powders up to a third temperature and introducing a second oxidizing gas including oxygen or ozone, thereby obtaining second dehydroxylated powders. The second dehydroxylated powders are heated up to a fourth temperature to obtain a vitrified body. The vitrified body is cooled to obtain the quartz glass with low content of hydroxyl and high purity. The quartz glass prepared by the above method has low content of hydroxyl and high purity. A quartz glass with low content of hydroxyl and high purity is also provided.

A quartz glass crucible (1) includes: a crucible body (10) made of silica glass; and a crystallization-accelerator-containing layer (13) formed on an outer surface of the crucible body (10). A concentration of a crystallization accelerator contained in the crystallization-accelerator-containing layer (13) is 1.0×10.sup.13 atoms/cm.sup.2 or more and 4.8×10.sup.15 atoms/cm.sup.2 or less. The quarts glass crucible is intended to be capable of not only enduring a single crystal pulling-up process that takes a very long time, such as multi-pulling, but also stably controlling the oxygen concentration and crystal diameter of a silicon single crystal by eliminating a gap between the carbon susceptor and the crucible as much as possible.

In an exemplary embodiment, a quartz glass crucible 1 includes: a cylindrical crucible body 10 which has a bottom and is made of quartz glass; and crystallization-accelerator-containing coating films 13A and 13B which are formed on surfaces of the crucible body 10 so as to cause crystallization-accelerator-enriched layers to be formed in the vicinity of the surfaces of the crucible body 10 by heating during a step of pulling up a silicon single crystal by a Czochralski method. The quartz glass crucible is capable of withstanding a single crystal pull-up step undertaken for a very long period of time, such as multi-pulling, and a manufacturing method thereof.

A method for producing a solid body of glass is described. The method comprises providing a polymerisable composition, curing the polymerisable composition to obtain a cured body, subjecting the cured body to thermal debinding to substantially remove the organic components in the cured body, and subjecting the cured body to sintering to obtain a solid body of silica glass. The polymerisable composition one or more at least partially organic polymerisable compound(s) which form a liquid composition at operating temperature and a solid source of silica as colloidal silica particles or silica glass micro-/nanoparticles dispersed in the liquid composition. The one or more at least partially organic polymerisable compounds comprises at least one organosilicon compound as a second source of silica that is liquid or solubilisable in the liquid composition at operating temperature to thereby increase the silica loading of the cured body prior to sintering. Compositions and methods for producing solid glass objects by additive manufacturing are also described.

A method for producing a solid body of glass is described. The method comprises providing a polymerisable composition, curing the polymerisable composition to obtain a cured body, subjecting the cured body to thermal debinding to substantially remove the organic components in the cured body, and subjecting the cured body to sintering to obtain a solid body of silica glass. The polymerisable composition one or more at least partially organic polymerisable compound(s) which form a liquid composition at operating temperature and a solid source of silica as colloidal silica particles or silica glass micro-/nanoparticles dispersed in the liquid composition. The one or more at least partially organic polymerisable compounds comprises at least one organosilicon compound as a second source of silica that is liquid or solubilisable in the liquid composition at operating temperature to thereby increase the silica loading of the cured body prior to sintering. Compositions and methods for producing solid glass objects by additive manufacturing are also described.

An optical fiber according to an embodiment includes a core, a cladding, and a coating layer. At the boundary between the core and the cladding, the local sound velocity decreases in the direction from the core side toward the cladding side. At least in the cladding, the local sound velocity changes continuously in a radial direction. Further, the line width of the Brillouin gain of the light beam guided by the fundamental mode is 60 MHz or more.

An object is to obtain an optical fiber having a small diameter and suppressing the increase of a microbending loss of the optical fiber. The optical fiber includes: a core portion made of silica glass; a cladding portion made of silica glass, the cladding portion covering the outer periphery of the core portion and having a refractive index smaller than a maximum refractive index of the core portion; and a coating portion covering the outer periphery of the cladding portion. The outer diameter of the cladding portion is 100 μm or smaller, the relative refractive-index difference Δ1 of the core portion is 0.5% or smaller, and the thickness of the coating portion is 10 μm or larger.

An object is to obtain an optical fiber having a small diameter and suppressing the increase of a microbending loss of the optical fiber. The optical fiber includes: a core portion made of silica glass; a cladding portion made of silica glass, the cladding portion covering the outer periphery of the core portion and having a refractive index smaller than a maximum refractive index of the core portion; and a coating portion covering the outer periphery of the cladding portion. The outer diameter of the cladding portion is 100 μm or smaller, the relative refractive-index difference Δ1 of the core portion is 0.5% or smaller, and the thickness of the coating portion is 10 μm or larger.

A method for producing rare earth metal-doped quartz glass includes the steps of (a) providing a blank of the rare earth metal-doped quartz glass, and (b) homogenizing the blank by softening the blank zone by zone in a heating zone and by twisting the softened zone along a rotation axis. Some rare earth metals, however, show a discoloration of the quartz glass, which hints at an unforeseeable and undesired change in the chemical composition or possibly at an inhomogeneous distribution of the dopants. To avoid this drawback and to provide a modified method which ensures the production of rare earth metal-doped quartz glass with reproducible properties, during homogenization according to method step (b), the blank is softened under the action of an oxidizingly acting or a neutral plasma.