The Furukawa Electric Co., Ltd.

Akira Iino

Fumio Takahashi

Jun-ichi Tamura

Kazuhisa Kashihara

Akira Matsuda

Masahide Kuwabara

Masato Oku

Katsumi Orimo

Hideyo Kawazoe

Ryotomo Sirakawa

Two or more optical waveguides are placed in a treatment vessel. The optical waveguides in the treatment vessel are treated with a chemical substance containing at least one of deuterium, hydrogen, and a compound thereof. The treating includes causing molecules of the chemical substance to diffuse into the optical waveguides, causing the molecules of the chemical substance that have diffused into the optical waveguides to react with structural defects that exist in a portion, through which light propagates, of the optical waveguides, and removing from the optical waveguides molecules of the chemical substance that do not react with the structural defect.

Method of manufacturing optical waveguide

A low attenuation optical fiber which falls within 2-14 ps/nm/km in absolute value of dispersion over the full wavelength range of 1530-1565 nm and no more than 0.25 dB/km of transmission loss at 1550 nm of wavelength at ordinary temperature and relative humidity, and still remains no more than 0.25 dB/km of transmission loss at 1550 nm or 1520 nm after its being long-enough exposed under ordinary atmospheric pressure consisting substantially of hydrogen; and which further comprises a polarization mode dispersion (PMD) of no more than 0.5 ps/&#x221a;{square root over (k)}m at a wavelength of 1550 nm and a loss increase of no more than 40 dB/m in a bending diameter of 20 mm.

Low attenuation optical fiber

A low attenuation optical fiber which falls within 2-14 ps/nm/km in absolute value of dispersion over the full wavelength range of 1530-1565 nm and no more than 0.25 dB/km of transmission loss at 1550 nm of wavelength at ordinary temperature and relative humidity, and still remains no more than 0.25 dB/km of transmission loss at 1550 nm or 1520 nm after its being long-enough exposed under ordinary atmospheric pressure consisting substantially of hydrogen; and which further comprises a polarization mode dispersion (PMD) of no more than 0.5 ps/km at a wavelength of 1550 nm and a loss increase of no more than 40 dB/m in a bending diameter of 20 mm.

In the optical fiber, the concentration of fluorine doped in the core portion is made nonuniform in the radial direction to be greater at the center portion of the core portion and less at the outer circumferential portion of the core portion. As a result, the distribution of the refractive index of the core portion and the cladding portion before the process of transparent glassification becomes a profile which is high at the outer circumferential portion of the core portion and which is low at the center portion. The reduction of the refractive index at the outer circumferential portion of the core portion due to the dispersion of the GeO.sub.2 etc., the oxide included in the core portion, in the cladding portion in the transparent glassification processed is and as a result, the profile of the refractive index of the core portion becomes one which sticks out in a step form with respect to the cladding portion.

Optical fiber and process of producing same

An optical fiber cable free from a generation of a microbent during manufacturing, and in which an impregnation of hydrogen and/or water to a cladding is prevented, and having high electrical conduction, tolerance to heat and mechanical strength, and a process for making same. The optical fiber cable includes a silica based glass optical fiber including a core and a cladding, a thin carbon coating formed on an outer surface of the optical fiber, and an electrically conductive coating formed on an outer surface of the carbon coating. The carbon coating functions as a layer for preventing the impregnation of hydrogen and/or water to the optical fiber, and the conductive coating functions as a heat tolerance member, a conductive member, and a mechanical support member. The carbon coating is preferably formed as an amorphous carbon layer. Preferably, the conductive coating can be made of materials having a good contact with the carbon coating, a high conductivity, a high heat tolerance, and a high strength, and can be formed as thin as possible. The conductive coating can be formed by a plurality of different metal layers having different thickness.

Optical fiber cable coated with conductive metal coating and process

A method of fabricating a porous glass rod having a reaction vessel including an elevational passage from an exhaust port of the vessel side and the top of the vessel over the interior and a burner mounted at the end in the vessel for forming glass fine particles, and a target elevationally movable and rotatably inserted from the passage into the vessel which has injecting to accumulate glass fine particles produced through the burner to form the porous glass rod at the lower end of the target rotated at a predetermined position in the reactor, and drawing the target in response to the growing velocity of the porous glass rod, wherein downward gas stream is produced along the outer periphery of the conduit in the vessel. The method is conducted by an apparatus for fabricating the glass rod. The method and apparatus can stabilize the fluidity in a reaction vessel to stabilize the outer diameter and the refractive index distribution of the glass rod in the longitudinal direction.

Growing community of inventors

Tokyo, Japan

Akira Iino