Fujikura Limited

Nippon Telegraph and Telephone Corporation

Naoki Shamoto

Kuniharu Himeno

Takashi Tsumanuma

Hideo Suzuki

Kazuhiko Aikawa

Akira Wada

Kazuo Sanada

Katsuaki Izoe

Manabu Kudoh

Katsuyuki Seto

Toshiyuki Tanaka

Kouji Tanaka

Yasuyuki Sugawara

Masaaki Kawase

Fumihiko Nishimura

Hiromichi Shinohara

Shigeru Emori

Tadayuki Inaba

A radiation resistant single-mode optical fiber has a core and a cladding, each made of fluorine-doped silica glass, in which a chlorine concentration of the core is at least 0.01 ppm, a relative refractive index difference of the core based on the refractive index for silica is between &#x2212;0.30% and &#x2212;0.10%, a relative refractive index difference of the core based on the refractive index for the cladding is between 0.3% and 0.5%, a cutoff wavelength is 1.27 &#x3bc;m or below, and a bending loss at a wavelength of 1.3 &#x3bc;m and a bending diameter of 20 mm is 0.5 dB/m or less.

Radiation resistant single-mode optical fiber and method of manufacturing thereof

The present invention provides a polarization maintaining optical fiber of which polarization crosstalk characteristic is not deteriorated after fusing two or more polarization maintaining optical fibers, and provides a method for producing a preform thereof. The polarization maintaining optical fiber includes two stress applying portions disposed in a cladding around a core, in which an angle formed by a line connecting the center of one of the stress applying portions with the center of the core and a line connecting the center of the other stress applying portion with the center of the core is 3 degrees or less. The preform is produced by forming one insertion hole in a cladding element and then rotating the preform 180 degrees around a core element without moving the drilling tool, followed by forming the other insertion hole in the cladding element and then inserting stress applying elements into the insertion holes.

Polarization maintaining optical fiber and production method for polarization maintaining optical fiber preform

An optical fiber for preserving the plane of polarization including a cladding and a stress imparting part disposed in the cladding, the stress imparting part comprising a base material including B O . The average concentration of B O in the base material of the stress imparting part is in a range between about 17 and 21 wt. %, and the maximum concentration of B O in the base material is in a range between about 17 and 22 wt. %. The optical fiber has excellent polarization plane preserving properties, and no concave portion is generated in its stress imparting part even under wet heat conditions.

Optical fiber for preserving plane of polarization

An image fiber preform for use in an image fiber according to the present invention includes a plurality of optical fiber strands, each optical fiber strand including a silica glass core which contains a dopant for increasing a refractive index of the core and a silica glass cladding surrounding the silica glass core, the silica glass cladding containing a fluorine dopant for decreasing a refractive index of the cladding, the cladding having an outer peripheral surface, and a quartz tube in which the optical fibers are closely arranged, wherein the cladding has a concentration of the fluorine dopant which decreases radially outward toward the outer peripheral surface of the cladding. in the present invention, an image fiber prepared from the image fiber preform and fabrication processes for the image fiber preform and the image fiber are provided.

Image fiber, image fiber preform, and manufacturing processes thereof

An optical fiber cable includes a flexible pipe of a plastics material, and a group of optical fibers loosely mounted within an axial bore of the pipe and held in contact with an inner surface of a peripheral wall of the pipe. At least one elongated flexible reinforcing member is embedded in the peripheral wall of the pipe and extends along a longitudinal axis of the cable, the reinforcing member being disposed in the vicinity of the group of optical fibers and made of a material having a higher Young's modulus than that of the plastics material of which the pipe is made. The optical fiber cable has a neutral axis extending through the bore of the pipe and defining a line of zero stress when the cable is bent longitudinally in a direction to dispose the reinforcing member radially inwardly of the group of optical fibers. The group of optical fibers are disposed on the neutral axis, so that the optical fibers are not subjected to axial contraction or elongation when the cable is bent in the direction.

Optical fiber cable having a neutral axis defining a zero stress

Growing community of inventors

Sakura, Japan

Naoki Shamoto