The Furukawa Electric Co., Ltd.

Hideya Moridaira

Kazuhiko Kurusu

Yoshinori Ishida

Masahide Kuwabara

Junichi Tamura

Fumio Takahashi

Iwao Shimotakahara

Yoshihiro Inoue

Nobuaki Orita

Akihiro Kanao

Taeko Shibuta

Satoru Ise

A porous layer is formed by depositing a silica glass particle around a core rod. The porous layer is dehydrated. The dehydrated porous layer is sintered under a decreased pressure until the dehydrated porous layer becomes a translucent glass layer containing a closed pore. The translucent glass layer is vitrified under an ambient atmosphere including an inert gas other than a helium gas.

Optical fiber preform, method of manufacturing optical fiber preform, and method of manufacturing optical fiber

A method of manufacturing a single mode optical fiber formed of a silica-based glass and including a glass part having a central core and a cladding region. The method including heating an optical fiber preform in a heating furnace including a first heater to melt the optical fiber preform, and fiber drawing an optical fiber from the molten optical fiber preform. The method further comprises continuously cooling the drawn optical fiber starting with a meniscus portion in which diameter is decreased from 90% of the preform diameter to 5% of the preform diameter to a portion where the drawn optical fiber has a temperature of 1,200&#xb0; C. at a cooling rate of 1,000 to 3,000&#xb0; C. /sec.

Method of manufacturing single mode optical fiber

An optical fiber having a small increase in loss at a wavelength of approximately 1400 nm involved in a deuterium treatment is provided, and an evaluation method to decide whether an optical fiber is that having such a loss increase, and a fabrication method of an optical fiber having a small increase in such a loss are also provided. An optical fiber according to the present invention comprises a core composed of a silica glass doped with at least germanium and a cladding composed of a silica glass surrounding it. The optical fiber is exposed to an atmosphere containing hydrogen or deuterium to diffuse hydrogen molecules or deuterium molecules in the optical fiber, and after that, the outer periphery of the glass region of the optical fiber is etched to an outer diameter of 50 &#x3bc;m, and then the electron spin density of PORs is 1&#xd7;10spins/g or less when the glass region is measured by the electron-spin resonance method.

Optical fiber, evaluation and fabrication method thereof

An optical fiber characterized by a cutoff wavelength of 1310 nm or less, a transmission loss of 0.40 dB/km or less at the wavelength of 1385 nm before hydrogen ageing, a transmission loss of 0.40 dB/km or less in the wavelength range of 1310 nm to 1625 nm after hydrogen ageing, and an electron spin density of the Non-Bridging Oxygen Hole Center of 1&#xd7;10spins/g or less measured by the electron spin resonance method after the diameter of the optical fiber is made to be about 50 &#x3bc;m by etching in diluted hydrofluoric acid, that having high reliability of hydrogen-proof characteristic suitable for WDM transmission in 1310 nm to 1625 nm and the method of evaluating the optical fiber are offered.

Optical fiber and evaluation method thereof

An optical fiber having a length of one kilometer or more with average transmission loss at a wavelength of 1383 nm being less than average transmission loss at a wavelength of 1310 nm, wherein a maximum value of a transmission loss at the wavelength of 1383 nm of any one kilometer section along the entire length of the optical fiber does not exceed the average transmission loss at the wavelength of 1383 nm along the entire length of the optical fiber by 0.03 dB/km or more.

Optical fiber for WDM system and manufacturing method thereof

In a single mode optical fiber formed of a silica-based glass and including a glass part having a central core and a cladding region, the density of non bridging oxygen hole center in the glass part is not higher than 1.0&#xd7;10spins/g in terms of the spin density measured by an electron spin resonance method.

Single mode optical fiber, method of manufacturing the same, and apparatus for manufacturing the same

An optical fiber includes a first core having a relative refractive index difference of larger than 0.36%, and a cladding. The optical fiber has fiber cut-off wavelength &#x3bb;c of more than 1350 nm, cable cut-off wavelength &#x3bb;cc of less than 1285 nm, bending loss at a wavelength of 1625 nm of not more than 10 dB/km when wound at a diameter of 20 mm, transmission loss at a wavelength range of 1285 to 1625 nm of not more than 0.40 dB/km, transmission loss at a wavelength of 1383 nm less than transmission loss at a wavelength of 1310 nm, and difference in transmission loss at a wavelength of 1383 nm of not more than 0.04 dB/km before and after exposure to hydrogen. The lower bending loss of the optical fiber provides an optical fiber cable for use in a WDM transmission in wavelength range of 1285 to 1625 nm.

Optical fiber having a lower bending loss

An optical fiber for forming an optical transmission line suitable for the wavelength division multiplexing transmission by connecting to a positive dispersion optical fiber is provided. Outside a first glass layer ( ), a second glass layer ( ), a third glass layer ( ) and a fourth glass layer ( ) are sequentially disposed. The fourth glass layer ( ) is to be a reference layer for a standard of a refractive index. A relative refractive index difference &Dgr; of the first glass layer to the reference layer is set to 1.6% to 2.6%, inclusive, a relative refractive index difference &Dgr; of the second glass layer is set to&minus;0.65% to &minus;0.4%, inclusive, and a relative refractive index difference &Dgr; of the third glass layer is set to 0.15% to 0.5%, inclusive.

Optical fiber and optical transmission line using the optical fiber

An optical fiber for forming an optical transmission line suitable for the wavelength division multiplexing transmission by connecting to a positive dispersion optical fiber is provided. Outside a first glass layer ( ), a second glass layer ( ), a third glass layer ( ) and a fourth glass layer ( ) are sequentially disposed. The fourth glass layer ( ) is to be a reference layer for a standard of a refractive index. A relative refractive index difference &Dgr; of the first glass layer to the reference layer is set 1.6% to 2.6%, inclusive, a relative refractive index difference &Dgr; of the second glass layer is set &minus;0.65% to &minus;0.4%, inclusive, and a relative refractive index difference &Dgr; of the third glass layer is set 0.15% to 0.5%, inclusive.

Growing community of inventors

Tokyo, Japan

Hideya Moridaira