Nippon Telegraph and Telephone Public Corporation

Sumitomo Electric Industries, Limited

Nitto Electric Industrial Co., Ltd.

Fujitsu Corporation

The Furukawa Electric Co., Ltd.

Tokyo Nippon Telegraph Public Corporation

Nobuo Inagaki

Yoshikazu Ishii

Seizi Hattori

Minoru Watanabe

Naoki Yoshioka

Takao Kimura

Mitsuo Yoshihara

Fumihiko Kato

Hiroo Kanamori

Michihisa Kyoto

Gotaro Tanaka

Shiro Kurosaki

Motohiro Nakahara

Takao Edahiro

Susumu Kawakami

Fumiaki Hanawa

Ryoichi Hara

Hiroshi Shimba

Shoichi Suto

Hiroyuki Suda

Wakatake Matsuda

Toshiaki Kuroha

Akira Terada

Akira Nohara

An improved method for fabricating an optical fiber preform by the vapor phase axial deposition (VAD) method, comprises forming core and cladding soots at the same time by the use of core and cladding burners. The improvement is that the cladding burner is designed so that at least one of the outlets for a feed material gas, a fuel gas, an auxiliary fuel gas, and an inert gas is composed of a plurality of openings. In this improved method, the temperature distribution from the boundary of the core soot to the periphery of the cladding soot is made smooth, and thus the cladding soot is prevented from cracking.

Method of fabricating optical fiber preforms

A coating material for optical glass fibers is disclosed. The material is comprised of 1,4-polybutadienes having functional groups or modified polybutadienes derived from the 1,4-polybutadienes having introduced therein polymerizable double bonds different from the double bonds present in the 1,4-polybutadienes.

Optical fibers coated with modified 1,4-polybutadienes

A method for producing a glass preform for optical fibers by heating a glass soot preform consisting of glass fine particles made mainly of silicon oxide, which method comprises the steps of:

Method for the production of glass preform for optical fibers

A method of fabricating an optical glass base material by injecting and depositing fine glass particles produced by chemically reacting glass stock which comprises means for growing the fine glass particles in a depositing direction to form porous rod-shaped base material, support means for supporting the porous rod-shaped base material after growing, and heat treatment means for sintering at least the outer periphery of the rod-shaped base material in a semisintering state before supporting the rod-shaped base material by said support means to harden the same. Thus, since the rod-shaped base material is held in the stable state through the support means, the mechanical strength of the base material is strengthened strength by the semisintering hardening through the heat treating means before being supported by the support means, the base material is not deformed nor damaged in the supported state, and a large base material may be fabricated.

Method of fabricating optical glass base material and apparatus for

A process for producing an optical glass product having a predetermined distribution of refractive index in the interior of the product is disclosed. The process comprises the steps of:

Process for producing optical glass product

Manufacturing method of doped silica glass suitable for optical fiber wherein quartz powder or SiO.sub.2 glass fine particles are exposed to a gas for producing the doped silica glass containing SiCl.sub.4, a gaseous additive and water vapor (H.sub.2 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 PbO.sub.2, SnO.sub.2, 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.degree.-90.degree. 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

Coated optical glass fibers are described, wherein the coating composition comprises an unsaturated polyester containing at least one of (1) polyethylene glycol or polypropylene glycol having an average molecular weight of from 200 to 1,000 as a glycol component, (2) a long chain saturated aliphatic dibasic acid containing 12 or more carbon atoms as saturated polybasic acid component, and an acrylate or methacrylate, and (3) a long chain saturated aliphatic dibasic acid containing 6 or more carbon atoms as a saturated polybasic acid component and a long chain aliphatic dihydric alcohol containing 4 or more carbon atoms as a glycol component; and an acrylate or methacrylate.

Coated optical glass fibers and method for production thereof

A method of roducing .gamma.-Fe.sub.2 O.sub.3 magnetic disk medium of continuous thin film is provided, in which a deposition source is deposited on an opposed Al-alloy substrate by means of a reactive vacuum deposition technique and the deposited film is thermally treated so as to be the magnetic disk medium. As the deposition source, a ferroalloy containing about 1 to 10 at.% Ti and about 0.5 to 5 at.% Co is employed.

Method of producing magnetic thin film

In the process of sputtering of an iron target in an atmosphere composed of a mixed gas containing a rare gas and oxygen, the oxygen partial pressure is regulated prior to both presputtering and main sputtering, by which ferromagnetic oxide Fe.sub.3 O.sub.4 is deposited on a substrate in one process. By setting the temperature of the substrate at 150.degree. to 250.degree. C, the coercive force and the squareness ratio of the oxide film is greatly enhanced. By using the oxide film as a medium of a magnetic disk storage, a magnetic recording and storage device of excellent characteristics can be obtained.

Method of making a magnetic oxide film

A magnetic oxide film manufacturing method is disclosed which involves the steps of sputtering a target made of iron and aluminum to form a film of non-magnetic iron oxide (.alpha.-Fe.sub.2 O.sub.3) and reducing the film to obtain a magnetic oxide film. When a target made of iron and aluminum is employed, it is possible to obtain a high coercive force magnetic oxide film which is highly adhesive to a substrate, excellent in surface roughness and less than 0.3.mu.m in thickness. Accordingly, it is possible to obtain a magnetic disk of high magnetic recording density.

Method of making a magnetic oxide film with high coercive force

Growing community of inventors

Ibaraki, Japan

Nobuo Inagaki