An optical fiber having a core comprising silica and greater than 1.5 wt % chlorine and less than 0.5 wt % F, said core having a refractive index .sub.1MAX, and a inner cladding region having refractive index .sub.2MIN surrounding the core, where .sub.1MAX>.sub.2MIN.

To provide a method of sintering an optical fiber porous glass base material, capable of sufficient dehydration and reducing a transmission loss caused by residual moisture by efficiently transferring heat from the heater to the base material during a process in dehydration/sintering for an optical fiber porous glass base material, a porous glass base material having a heat shield plate installed in a vicinity of a lower end is vertically inserted into a furnace core tube provided with a heater along an outer circumference, and heating using the heater is performed. The heat shield plate has an outer diameter which is 70% or larger than a diameter of the porous glass base material and smaller than an inner diameter of the furnace core tube.

According to some embodiments method for making an optical fiber preform comprises the steps of: (i) placing a plurality of rods with an outer surface having a coefficient of friction 0.02COF0.3 into an inner cavity of an apparatus; (ii) placing particulate glass material in the inner cavity between the rods and an inner wall of the mold cavity; and (iii) applying pressure against the particulate glass material to press the particulate glass material against the plurality of rods.

A process for manufacturing glass articles from powder at low temperatures includes the steps of preparing a slurry of powder suspended in a liquid; depositing the slurry on a substrate; drying the slurry to form a layer on the substrate; depositing slurry on the layer; drying the slurry deposited on the layer on the substrate to form another layer; repeating the steps of depositing a slurry and drying the to form a plurality of sequential layers on the substrate; and consolidating the plurality of sequential layers to form a glass article. The process requires a small manufacturing footprint, and facilitates the manufacture of very large near-net shape glass articles.

A manufacturing method for an optical fiber preform includes forming a porous material made of fine silica glass particles surrounding a plurality of glass rods; and sintering the porous material, wherein the forming the porous material includes forming the porous material such that two or more of the plurality of glass rods protrude from the porous material, and the sintering includes supporting end portions of protruding sides of the two or more protruding glass rods collectively with a support jig, and performing the sintering. With this, a reduction in manufacturing yield is suppressed.

A quartz glass body and a process for the preparation of a quartz glass body is disclosed. In one aspect, the process includes providing a silicon dioxide granulate from a pyrogenic silicon dioxide powder, making a glass melt out of the silicon dioxide granulate and making a quartz glass body out of at least part of the glass melt. In at least one process a silicon component different from silicon dioxide is added. One aspect further relates to a quartz glass body which is obtainable by this process. A light guide, an illuminant and a formed body, are each obtainable by further processing of the quartz glass body.

A method of forming an optical fiber includes the steps of forming a silica-based soot blank with at least one silica-based soot core cane at least partially embedded in the soot blank. The soot blank with the soot core cane positioned therein is consolidated to form a preform. The preform is then drawn to form an optical fiber. The soot core cane preferably has an average bulk density within 10% of the bulk density of the soot blank, and more preferably within 5% of the bulk density of the soot blank.

Optical preforms and methods for forming optical preforms are disclosed. According to one embodiment, a method for producing an optical preform includes compressing silica-based glass soot to form a porous optical preform comprising a soot compact. The porous optical preform is heated to a dwell temperature greater than or equal to 100 C. Thereafter, the porous optical preform is humidified at the dwell temperature in a water-containing atmosphere having a dew point greater than or equal to 30 C. to form a humidified porous optical preform. The soot compact portion of the humidified porous optical preform generally comprises greater than or equal to 0.5 wt. % water.

A method for forming an optical quality glass is provided. The method includes contacting silica soot particles with a basic additive, forming a silica soot compact, and removing the basic additive from the silica soot compact. A method of forming a cladding portion of an optical fiber preform is also provided.

An optical fiber having a core comprising silica and greater than 1.5 wt % chlorine and less than 0.5 wt % F, said core having a refractive index .sub.1MAX, and a inner cladding region having refractive index .sub.2MIN surrounding the core, where .sub.1MAX>.sub.2MIN.