A quartz glass crucible (1) has a structure wherein a peak of a distribution of a total concentration of Na, K, and Ca in a depth direction from an inner surface (10i) of the crucible is present at a position deeper than the inner surface (10i). In an exemplary embodiment, the quartz glass crucible is capable of improving the yield of a silicon single crystal by suppressing peeling-off of brown rings.

A method for manufacturing an optical fibre includes placing the powdery substance compactly in the fluorine doped tube to form a core section. The core section of the glass preform is defined along a longitudinal axis of the glass preform. In particular, the fluorine doped tube is sintered to solidify the powdery substance. Moreover, the glass preform is heated at high temperature to draw the optical fibre.

A method for manufacturing of an optical fibre preform (100) using optimized core particles includes optimization of particles of calcium aluminum silicate powder (104), utilizing the optimized core particles, sintering the optimized core particles inside a fluorine doped glass tube (106) and drawing of an optical fibre. Particularly, the optimization of the particles of calcium aluminum silicate powder (104) facilitates formation of the optimized core particles and the optimized core particles are filled inside the fluorine doped glass tube (106). Moreover, sintering of the optimized core particles solidifies and adheres smoothly with the fluorine doped glass tube (106) for manufacturing of the optical fibre preform (100).

A method for drawing an optical fibre from an optical fibre preform with a core section, a cladding section, a first gap and a second gap. The optical fibre preform is attached to an optical fibre draw tower through a handle. In addition, the optical fibre preform is connected to a vacuum system to supply and remove gas from the first gap and the second gap. Moreover, the gas is supplied to create a thermal barrier between the core section and the cladding section during heating of the optical fibre preform. Further, the optical fibre preform is heated inside a heating furnace to draw the optical fibre from the optical fibre preform.

A reduced diameter optical fibre preform positioned along a longitudinal axis includes a core section defined around the longitudinal axis and a cladding section circumferentially surrounding the core section. The reduced diameter optical fibre preform is manufactured by utilizing a calcium aluminum silicate rod and a fluorine doped glass cylinder.

An optical fibre including a core region defined along a central longitudinal axis of the optical fibre and a cladding region concentrically surrounds the core region of the optical fibre. In particular, the core region has a first radius r.sub.1 and a first refractive index n.sub.1. Moreover, the cladding has a second radius r.sub.2 and a second refractive index n.sub.2. Furthermore, the optical fibre has a step index profile.

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 optical fiber containing alkali metal elements or the like in which Rayleigh scattering loss can be reduced is provided. An optical fiber includes a core composed of silica glass and a cladding which surrounds the core, has a refractive index lower than a refractive index of the core, and is composed of silica glass containing fluorine. The core contains a first group of dopants and a second group of dopants having a diffusion coefficient lower than a diffusion coefficient of the first group of dopants. The difference between the maximum value and the minimum value of residual stress in the optical fiber is 150 MPa or less.

A method for manufacturing an optical fiber preform includes: adding an alkali metal element or an alkaline earth metal element to an inner surface of a glass pipe made of silica-based glass; reducing a diameter of the glass pipe after the adding; etching an inner surface of a continuous section of the glass pipe in a longitudinal direction after the reducing; and collapsing the glass pipe after the etching. At least one of the adding, the reducing, the etching, and the collapsing includes performing a local etching on an inner surface of a section of the glass pipe that is shorter than the continuous section.

The present disclosure relates to a method for forming a glass, ceramic or composite material. The method may involve initially forming a plurality of tubes and then performing a coating operation to coat the plurality of tubes with materials containing metal or metalloid elements, including inorganic compounds, organometallic compounds, or coordination complexes to form coated tubes. The method may further include performing at least one of a thermal operation or a thermochemical operation on the coated tubes to form a solid glass, ceramic, or composite structure with dimensions representing at least one of a rod or fiber.