A system and method for nitridizing a glass article includes supplying a source of a nitridizing gas including gaseous NH.sub.3 to a glass article supported within a furnace assembly and heating the glass article. In some embodiments, the system includes a handle assembly configured to support the glass article within the furnace assembly and a gas supply conduit carried by the handle and configured to supply the nitridizing gas to the glass article. In some embodiments, a method of nitridizing a glass article includes supplying the nitridizing gas such that a residence time of the nitridizing gas at temperatures greater than 500 C. corresponds to a predetermined time period. In some embodiments, a method of nitridizing a glass article includes supplying the nitridizing gas such that the glass articles is exposed to the nitridizing gas within a contact time t.sub.c.

The invention relates to a device, system, and method for forming a core-rod for optical fibers by collapsing a tube comprising deposited layers of silica to form the core-rod. The device comprises an elongate cavity, an elongate cylindrical carbon liner bounding the cavity, the liner connecting to a frame of the device at opposing end portions, a heating element in a heating element space, surrounding the liner, the liner separating the heating element space from the cavity, a ring of a refractory material, fixated to the frame, surrounding a part of a length of the cavity, the liner being provided such that an inner surface portion at a first end portion of the liner mates with a cylindrical outer surface portion of the ring such that the liner can axially move with the first end portion thereof along the outer surface portion of the ring.

A porous glass base material sintering method comprising measuring a feeding speed V.sub.f of a porous glass base material and a movement speed V.sub.w of a bottom end of the glass base material; performing a sintering treatment of the porous glass base material presetting, for each feeding distance L of the porous glass base material, a greater-than-1 target value .sub.S (L) of an elongation rate in a straight body portion of the porous glass base material calculated based on a ratio V.sub.w/V.sub.f, and controlling at least one of a temperature of the heating furnace and a feeding speed of the porous glass base material such that a measured value of the elongation rate of the porous glass base material matches with the target value .sub.S (L).

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.

A method of preparing an optical preform, comprises the steps of: positioning an optical preform comprising silica within a cavity of a furnace; passing an etchant gas into the furnace and at least one of through an open channel defined in the optical preform and around the optical preform; and passing a neutralizing gas into the cavity of the furnace, the neutralizing gas configured to neutralize the etchant gas.

Provided is an elongating method for elongating a glass base material by heating the same while moving the same downward within an elongating apparatus, the glass base material including a transparent tapered section, wherein the transparent tapered section is located at an upper end of the glass base material and has an end face to which a suspension dummy formed from a glass pole is welded, the elongating method comprising steps for: starting to elongate the glass base material by heating the same, starting from a lower-end side thereof, by causing the glass base material to pass through a range within the elongating apparatus in which a preset elongating process temperature or higher is maintained; and after the tapered section enters the range, ending the elongating of the glass base material before the end face enters the range.

The present disclosure relates to a method and an extrusion apparatus (100, 200) to manufacture a soot preform (130). The extrusion apparatus (100 and 200) includes a feed-hopper (104) to feed silica slurry (102) which is pushed within the barrel (106), an iris frame (116) exhibiting a variable diameter to control a diameter of the soot preform (130), drying furnace (118), debinding furnace (122) eliminates moisture and one or more stabilized binders in the soot preform (130) to obtain a glass preform (138) from which an optical fiber (142) is drawn.

A system for positioning an optical preform in a furnace is provided that includes an upper muffle and a downfeed handle assembly with a tube defining a first end and a second end, the second end extending into the upper muffle. A handle is disposed within the tube. A second end of the handle extends into the upper muffle and a seal assembly is positioned around both the tube and the handle. The first end of the handle extends through the seal assembly and a drive assembly is coupled with the downfeed handle.

The present disclosure is directed to a method of making an optical fiber with improved bend performance, the optical fiber having a core and at least one cladding layer, and a chlorine content in the in the last layer of the at least one cladding layer that is greater than 500 ppm by weight. The fiber is prepared using a mixture of a carrier gas, a gaseous chlorine source material and a gaseous reducing agent during the sintering of the last or outermost layer of the at least one cladding layer. The inclusion of the reducing gas into a mixture of the carrier gas and gaseous chlorine material reduces oxygen-rich defects that results in at least a 20% reduction in TTP during hydrogen aging testing.

One aspect relates to a method for the manufacture of doped quartz glass. Moreover, one aspect relates to quartz glass obtainable according to the method including providing a soot body, treating the soot body with a gas, heating an intermediate product and vitrifying an intermediate product.