Hitachi Cable, Inc.

Junkichi Nakagawa

Hiroshi Kajioka

Toshihide Tokunaga

Seiji Mizuniwa

Toshiya Toyoshima

Tomoki Inada

Masashi Fukumoto

In the single polarization optical fiber of the present invention, an elliptical jacket is composed of SiO.sub.2 +P.sub.2 O.sub.5 +B.sub.2 O.sub.3, whereby increase in transmission loss at long wavelength band is prevented. In the process for fabricating single polarization optical fibers of the invention, a starting silica tube is subjected to pressure reduction with an amount of pressure reduction in response to concentration of dopants P.sub.2 O.sub.5 +B.sub.2 O.sub.3, whereby an ellipticity of the resulting elliptical jacket is made to be a pertinent value.

Single polarization optical fibers

A single polarization optical fiber has an elliptical jacket composed of SiO.sub.2 +F.sub.2 O+P.sub.2 O.sub.5, whereby increase in transmission loss at a long wavelength band is prevented.

The present invention relates to the manufacturing process of semi-insulating gallium arsenide single crystal by pulling a seed crystal contacted with gallium arsenide melt which is obtained by heat-reacting gallium and arsenic in a crucible contained in a pressure container and is characteristic in providing a film layer of 8-20 mm thickness of melted boron oxide with less than 200 ppm water content under pressure controlled at 60 kg/cm.sup.2 and over during reaction and at 5-40 kg/cm.sup.2 during crystal growth in high purity inert gas atmosphere, and during said crystal growth, rotating said seed crystal and said crucible in the same direction, but said seed crystal being rotated 5-30 rpm faster than the said crucible, and setting the crystal growing plane of said seed crystal to be within .+-.3.degree. from {100} plane.

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Hitachi, Japan

Junkichi Nakagawa