Nippon Telegraph and Telephone Corporation

Nippon Telegraph and Telephone Public Corporation

Hiroyuki Suda

Motohiro Nakahara

Shuichi Shibata

Yasuyuki Inoue

Katsunari Okamoto

Masao Kawachi

Nobuo Inagaki

Norio Takato

Fumihiko Yamamoto

Fumiaki Hanawa

Shinichi Furukawa

Akira Morinaka

Shoichi Suto

An integrated optical waveguide circuit includes a substrate; an optical wavelength multiplexer and an optical power splitter formed on a same surface of the substrate. The optical wavelength multiplexer is composed of a first slab optical waveguide, a second slab optical waveguide, a single or a plurality of input optical waveguides connected to the first slab optical waveguide at one end of the first slab optical waveguide, a plurality of arrayed optical waveguides arranged in parallel and having different lengths and connected to the first slab optical waveguide and the second slab optical waveguide, and a plurality of output optical waveguides arranged in parallel and connected to the second slab optical waveguide. The optical power splitter is composed of the second slab optical waveguide, one or more input optical waveguides, and the plurality of output optical waveguides arranged in parallel and connected to the second slab optical waveguide.

Integrated optical waveguide circuit and optical branch line test system

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 deposed around the raw material supply orifice sequentially for forming a plurality of flames, respectively. The flame speed V.sub.k of a kth flame, the flame speed V.sub.k+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 multi-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

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 V.sub.k of a kth flame, the flame speed V.sub.k+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.

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

Growing community of inventors

Mito, Japan

Hiroyuki Suda