A rod-in-tube method for producing a glass preform for use in the fabrication of an optical fiber, which comprises steps of inserting a glass rod (13) as a core material in a glass tube (12) as a cladding material, fusing and closing one end of the cladding material, filling a gap between the core and cladding materials with an atmosphere containing at least one gaseous halogen-containing compound and then heating the core and cladding materials at a temperature not lower than 1,900°C to collapse the gap between them and to fuse them together, from which glass preform, an optical fiber with low attenuation of light transmission is fabricated.

Method for producing glass preform for optical fiber

The subject of this report is chemistry and engineering for the application of heterogeneous photocatalysts. The state of the art in catalysts are forms of titanium dioxide or modifications thereof, but work on other heterogeneous catalysts is included.

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Bibliography of Work on the Heterogeneous Photocatalytic Removal of Hazardous Compounds from Water and Air

This paper reviews the MCVD process, with special emphasis on fiber design and material choices, understanding of mechanisms involved in the process, process improvements, and performance.

An overview of the modified chemical vapor deposition (MCVD) process and performance

This invention is a rare earth doped optical amplifier with increased gain and lowered pump thresholds. The amplifying scheme is based on a 3 level lasing system rather than the more prevalent 4 level lasing system. Additionally, the transmission mode of the optical fiber at the pump wavelength has a radius which is substantially equal to or greater than the radius of the distribution profile of the rare earth ions in the fiber amplifier core. With the inventive amplifier, a gain of 37 dB and a saturation power of 11.3 dBm has been obtained with only 54 mW of launch power at λ=1.49 μm.

Erbium-doped fiber amplifier

An Overview of the Modified Chemical Vapor Deposition (MCVD) Process and Performance

PURPOSE: To carry out the high-speed spinning of an optical fiber having high reliability using a very simple apparatus in combination with a high-speed spinning apparatus, by passing an optical fiber immediately after spinning through an inorganic raw material gas, thereby reacting the gas at the surface of the fiber taking advantage of the remaining heat of the fiber. CONSTITUTION: He gas (carrier gas) 11 is bubbled in liquid TiCl 4 13 stored in the bubbler 12, and the TiCl 4 vapor 14 is blasted through the nozzle 15 to the surface of the optical fiber 18 having a definite diameter immediately after being spun from the optical fiber preform 17 with the spinning furnace 16. The vapor 14 is decomposed at the surface of the optical fiber by the remaining heat of spinning, oxidized to TiO 2 , and deposited to the surface of the fiber 18 to form a coating layer. The optical fiber 18 cooled by the endothermic reaction is passed through the die 2 containing the thermosetting resin 19 for coating. The resin 19 attached to the surface of the optical fiber 18 is baked, and cured in the furnace 21. COPYRIGHT: (C)1982,JPO&Japio

Manufacture of optical fiber

In an optical fiber preform fabrication method having the steps of decomposing a glass raw material in a flame so that fine glass particles are produced; depositing the fine glass particles on a seed rod to form a porous preform; and consolidating the porous preform into a transparent optical fiber preform, use is made of a burner having a raw material supply orifice for supplying the glass raw material and a plurality of flame forming orifices disposed around the raw material supply orifice sequentially for forming a plurality of flames, respectively. The flame speed Vk of a kth flame, the flame speed Vk+1 of a (k+1)th flame surrounding outwardly of the kth flame and the flow speed Vm of the glass raw material are determined in a suitable manner. The glass raw material is supplied to the maluti-flame produced by the burner in which the kth flame is positioned rearwardly of the (k+1)th flame to synthesize the fine glass particles.

Method, apparatus and burner for fabricating an optical fiber preform

Manufacturing method of doped silica glass suitable for optical fiber wherein quartz powder or SiO2 glass fine particles are exposed to a gas for producing the doped silica glass containing SiCl4, a gaseous additive and water vapor (H2 O) to add the dopant to the glass body, and then the resulting glass body is fused at a high temperature, thereby producing a transparent doped silica glass in which the production of the glass particles, the addition of the dopant, and the vitrification of the glass body are carried out by separate steps under respective suitable conditions. The manufacturing speed is remarkably increased because of the separate steps. The content of the dopant is not limited, but can be adjusted with any desired amount by changing the reaction time of dissolution. Dopant components like PbO2, SnO2, ZnO which were typically not added to the glass body can now be added thereto. Also, a method of manufacturing an optical fiber preform is disclosed wherein the doped silica glass is deposited and fused on a starting material which is inclined by an angle within a range of 5°-90° with respect to a blow-off direction of the flow of the doped silica glass to form a transparent doped silica glass body having a uniform outer diameter and a uniform boundary surface at a high synthesizing speed. This latter method aids mass production of optical fibers at low cost.

Fabrication methods of doped silica glass and optical fiber preform by using the doped silica glass

PURPOSE:To improve the radiation resistance of quartz glass for an optical fiber by exposing the glass to an atmosphere contg. hydrogen to bond hydrogen only to defects in the glass and to introduce a proper number of OH groups. CONSTITUTION:Glass for an optical fiber such as a molded body of quartz glass soot forming a porous glass base material for an optical fiber, a molded body of quartz glass forming a transparent glass base material for an optical fiber or a molded body of glass forming an optical fiber is exposed to an atmosphere contg. hydrogen to bond hydrogen only to defects in the glass and to introduce the irreducible minimum number of OH groups required. Thus, an optical fiber enduring a radiation environment is obtd.

Treatment of glass for optical fiber

A method of fabricating an optical fiber preform wherein a synthesizing torch is inclined between 10° and 60° with respect to the rotation axis of a seed rod. Moving the rod while rotating it, a glass raw material gas and a flame forming gas are blown out individually from the torch to synthesize glass particles which are deposited onto one end of the rod, so that a cylindrical porous preform is grown in the direction of the rotation axis of the rod. Then the porous preform is heated at a high temperature to vitrify the porous preform into a transparent optical fiber preform. At least one exhaust port is disposed at a distance of 1 mm to 50 mm from the periphery of the porous preform and in the vicinity of the growing surface of the porous preform. In fabricating the porous preform the outer diameter fluctuations are small, and the preform is formed stably without formation of cracking on the periphery of the preform.

Motohiro Nakahara

Papers

Manufacture of optical fiber

Method, apparatus and burner for fabricating an optical fiber preform

Fabrication methods of doped silica glass and optical fiber preform by using the doped silica glass

Treatment of glass for optical fiber

Method of fabricating multi-mode optical fiber preforms