The Furukawa Electric Co., Ltd.

Mitsuhiro Kawasaki

Yohei Uchida

Shuhei Hayami

Fumio Takahashi

Tomohiro Gonda

Toshiyuki Asai

Hiroaki Oonuma

Hiroki Otani

A method for cleaning a vaporizer that vaporizes, at normal temperature and pressure, a source material in a liquid state, and supplies the vaporized source material to a reactor through a supply pipe, includes a cleaning step of passing the source material to the vaporizer while maintaining the source material in a liquid state to clean the vaporizer.

Method for cleaning vaporizer and vaporization apparatus

A method for manufacturing an optical fiber preform includes: producing a core preform including a core portion made of transparent glass and a first cladding layer obtained by adding fluorine to the core portion; and forming, on an outer periphery of the first cladding layer, a second cladding layer made of glass having a refractive index higher than that of the first cladding layer. Further, a refractive index profile is formed in the first cladding layer due to a fluorine concentration profile, the refractive index profile being provided at least near a boundary surface with the second cladding layer and having a profile such that a refractive index difference between a refractive index of the first cladding layer and a refractive index of the second cladding layer decreases in accordance with a reduction in a distance from the boundary surface with the second cladding layer.

Method for manufacturing optical fiber preform, optical fiber preform, method for manufacturing optical fiber, and optical fiber

A multiple tube burner for synthesizing a porous material includes three or more glass tubes are arranged coaxially with one another, the glass tubes having a substantially circular shape on a cross section perpendicular to a longitudinal direction. Out of the three or more glass tubes, a first glass tube and a second glass tube that is arranged on an outer side of the first glass tube are connected with each other on a gas introducing side, and a thickness near a joint portion of the second glass tube connected with the first glass tube is thicker than a thickness of the second glass tube on the gas spouting side.

Multiple tube burner for synthesizing porous material and apparatus for synthesizing porous material

An optical fiber preform includes: a columnar portion having an approximately constant radius of r; and a taper portion located adjacent to the columnar portion in a lengthwise direction and having a radius decreasing along the lengthwise direction. The taper portion includes: a first taper portion including a portion having a radius varying between 0.9r and 0.6r; and a second taper portion including a portion having a radius varying between 0.4r and 0.15r. A diameter of the first taper portion in the portion having the radius varying between 0.9r and 0.6r decreases so as to form a maximum angle &#x3b8;1 between 40 degrees and 60 degrees with respect to the columnar portion, a diameter of the second taper portion in the portion having the radius varying between 0.4r and 0.15r decreases so as to form an average angle &#x3b8;2 between 5 degrees and 30 degrees with respect to a central axis in the lengthwise direction, and a volume of the taper portion is smaller than or equal to 45% of a volume of a column having a same outer diameter as a maximum outer diameter of the taper portion and having a same length as the taper portion.

Optical fiber preform and method of manufacturing optical fiber

The present invention provides an optical fiber of which a zero dispersion wavelength falls within a range of between 1,250 nm and 1,350 nm inclusive, transmission loss at 1,550 nm is equal to or less than 0.185 dB/km, chromatic dispersion at 1,550 nm is within the range of 19&#xb1;1 ps/nm&#xb7;km, a dispersion slope at 1,550 nm is equal to or less than 0.06 ps/nm&#xb7;km, an effective area Ais equal to or more than 105 &#x3bc;m, a cable cutoff wavelength &#x3bb;is equal to or less than 1,530 nm, polarization mode dispersion is equal to or less than 0.1 ps/km, and a loss when the optical fiber is wound on a mandrel having an outer diameter of 20 mm is equal to or less than 10 dB/m.

Optical fiber, method for manufacturing same and optical transmission channel

An optical fiber suitable for the WDM transmission in the wavelength bands of 1.31 &#x3bc;m and 1.55 &#x3bc;m is provided. An optical fiber is characterized by a zero dispersion wavelength of longer than 1330 nm and shorter than 1430 nm, a dispersion of not less than 6 ps/nm/km and not more than 15 ps/nm/km at a wavelength of 1550 nm, a ratio of a dispersion to a dispersion slope of not less than 200 nm and not mare than 400 nm at a wavelength of 1550 nm, a dispersion of not more than &#x2212;1 ps/nm/km and not less than&#x2212;8 ps/mn/km at 1300 nm, and a cutoff wavelength of 1300 nm or shorter.

Optical fiber and an optical transmission system using the optical fiber

The optical fiber includes a center core portion, a side core portion and clad portion, which has a dispersion value of 14-20 ps/nm/km at a wavelength of 1550 nm, a dispersion slope of 0.05-0.08 ps/nm /km at a wavelength of 1550 nm and a transmission attenuation of 0.2 dB/km or less at a wavelength of 1550 nm, wherein the relative refractive index difference &Dgr;1 between the center core portion and the clad portion is 0.25-0.50%, the relative refractive index difference &Dgr;2 between the side core portion and the clad portion is 0.05-0.30%, an inequality &Dgr;2<&Dgr;1 is satisfied, the ratio a/b between an outer diameter a of the center core portion and an outer diameter b of the side core portion is 0.3-0.7, and the effective core area Aeff at a wavelength of 1550 nm is 90 &mgr;m or larger.

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Tokyo, Japan

Mitsuhiro Kawasaki