A manufacturing method of an optical fiber preform used to produce an optical fiber includes: etching a surface of a core preform that forms a core of the optical fiber with a plasma flame in a chamber; obtaining a porous preform by depositing glass particles on an etched surface of the core preform to form an outside vapor-deposited layer that forms a cladding of the optical fiber in a state where the core preform is put into the chamber; and heating and sintering the porous preform. When obtaining the porous preform, the outside vapor-deposited layer is formed by repeatedly performing the deposition of the glass particles multiple times through supply of source material gas. In a first deposition among the multiple times of deposition of the glass particles, a flow rate of the source material gas is less than or equal to 50% of a stable value.

Preparation of halogen-doped silica is described. The preparation includes doping silica with high halogen concentration and sintering halogen-doped silica to a closed-pore state. The sintering includes a high pressure sintering treatment and a low pressure sintering treatment. The high pressure sintering treatment is conducted in the presence of a high partial pressure of a gas-phase halogen doping precursor and densifies a silica soot body to a partially consolidated state. The low pressure sintering treatment is conducted in the presence of a low partial pressure of gas-phase halogen doping precursor and transforms a partially consolidated silica body to a closed-pore state. The product halogen-doped silica glass exhibits little foaming when heated to form fibers in a draw process or core canes in a redraw process.

The present disclosure provides a method for fabrication of an optical fibre soot preform. The method includes production of silicon dioxide particles along with waste particulates. The silicon dioxide particles are produced using a precursor material in a combustion chamber. In addition, the method includes cooling of the silicon dioxide particles. Further, the method includes agglomeration of the silicon dioxide particles. Furthermore, the method includes separation of the waste particulates from the silicon dioxide particles. Moreover, the method includes dehydration of the silicon dioxide particles. Also, the method includes compaction of the silicon dioxide particles. The compaction of the silicon dioxide particles facilitates fabrication of the optical fibre soot preform.

A system and methods are described herein for preheating a preform in a preheater furnace and then transferring the preheated preform to a consolidation furnace for chemical treatment and sintering the preform into a clear glass which can be drawn into optical fiber. In addition, the preheater furnace is described herein which is configured to heat the preform per a predetermined heat-profile until the preform is uniformly heated to a temperature above 1000 C.

The invention relates to exemplary methods, devices, and systems for heating an elongate silica cylinder to form a core-rod for optical fibers. An exemplary heating device includes an elongate cavity, an elongate liner bounding the cavity, a heating element in a heating element space surrounding the liner, the liner separating the heating element space from the cavity, and a gas flushing device for effecting a flow of gas at least through the heating element space. An exemplary method includes providing the elongate silica cylinder such that it extends through the cavity, heating the cylinder locally beyond its softening temperature, and effecting a flow of argon and nitrogen gas during the heating.

An optical fiber includes: a core; and a cladding layer disposed on an outer circumference of the core. A Cl concentration in the cladding layer is 0.029 wt % to 0.098 wt %. In the optical fiber, 210 dB/km is satisfied at a wavelength of 430 nm where 1 is a value of transmission loss before exposure of the optical fiber to hydrogen and 2 is a value of transmission loss after the exposure.

A method of forming an optical element is provided. The method includes producing silica-based soot particles using chemical vapor deposition, the silica-based soot particles having an average particle size of between about 0.05 m and about 0.25 m. The method also includes forming a soot compact from the silica-based soot particles and doping the soot compact with a halogen in a closed system by contacting the silica-based soot compact with a halogen-containing gas in the closed system at a temperature of less than about 1200 C.

A method of manufacturing an optical fiber, the method includes drawing a first optical fiber preform at a first draw tension to produce a first alkali doped optical fiber and drawing the first optical fiber preform at a second draw tension to produce a second alkali doped optical fiber, measuring the attenuation of the first alkali doped optical fiber and the second alkali doped optical fiber such that the second alkali doped optical fiber has a lower attenuation. Additionally, the method includes setting the draw tension to the second draw tension and drawing a second optical fiber preform at the second draw tension to produce a third alkali doped optical fiber. The third alkali-doped optical fiber has an attenuation at 850 nm of about 1.50 dB/km or less and an attenuation at 1550 nm of about 0.155 dB/km or less.

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 present application provides a process of fabrication of erbium and ytterbium-co-doped multielements silica glass based cladding-pumped fiber for use as a highly efficient high power optical amplifier.