Abstract: A method for manufacturing deuterium-treated silica glass includes exposing silica glass to a deuterium-containing atmosphere for a predetermined period of time to diffuse deuterium molecules within the silica glass, maintaining the silica glass at 40° C. or higher, and cooling the silica glass to room temperature. The silica glass is a silica glass-based optical fiber having a core made of silica glass, where the core is positioned at a center of the optical fiber and contains at least germanium, and a clad made of silica glass, where the clad surrounds the core and has a lower refractive index than the core. A surface of the silica glass is covered with a resin coating.

Abstract: To provide a polyamide copolymer that is excellent in terms of rigidity after water absorption (water absorption rigidity) and rigidity under high temperature use (thermal rigidity). A polyamide copolymer comprising a dicarboxylic acid component unit containing an (a) adipic acid unit, a (b) isophthalic acid unit and a (c) 1,4-cyclohexanedicarboxylic acid unit, and a diamine component unit, wherein a relationship between a content (mol %) of the (b) and a content (mol %) of the (c) in a total of 100 mol % of the dicarboxylic acid component unit containing the (a), the (b) and the (c) satisfies following formula (1): (c)>(b)?0.1??(1).

Abstract: Provided is an optical fiber including: a core at a center thereof; a first cladding adjacent to the core to cover a circumference of the core; and a second cladding adjacent to the first cladding to cover a circumference of the first cladding, where 0.35%?(?1??2)?0.65%, 0.30%??1?0.55%, ?0.20%??2??0.05%, 0.22?a/b?0.34, and 4?b?|?2|?10 hold, and loss increase resulting when the optical fiber is wound on a mandrel having a diameter of 20 mm is 0.

Abstract: An optical fiber capable of suppressing an increase of a transmission loss after exposure of the optical fiber to hydrogen or deuterium is provided. The optical fiber has a core region, an inner cladding region surrounding the core region, a trench region surrounding the inner cladding region, an outer cladding region surrounding the trench region, and a refractive index varying region arranged between the inner cladding region and the trench region, the refractive index varying region having a refractive index gradually increasing from the trench region to the inner cladding region.

Abstract: Provided is an optical fiber including: a first core at a center thereof; a second core adjacent to the first core to cover a circumference of the first core; a third core adjacent to the second core to cover a circumference of the second core; and a cladding adjacent to the third core to cover a circumference of the third core, where conditions of 0.28%??1?0.4%, ?0.05%??2?0.05%, ?1.0%??3??0.5%, 3.8 ?m?a?4.5 ?m, 12 ?m?b?21 ?m, and 1.5 ?m?c-b?10 ?m hold, and loss increase resulting when the optical fiber is wound on a mandrel having a diameter of 20 mm is 0.

Abstract: Provided is an optical fiber including: a core at a center thereof; a first cladding adjacent to the core to cover a circumference of the core; and a second cladding adjacent to the first cladding to cover a circumference of the first cladding, where 0.35%?(?1??2)?0.65%, 0.30%??1?0.55%, ?0.20%??2??0.05%, 0.22?a/b?0.34, and 4?b?|?2|?10 hold, and loss increase resulting when the optical fiber is wound on a mandrel having a diameter of 20 mm is 0.

Abstract: The present invention can provide a polyamide composition that is more excellent in the heat resistance and tensile elongation of molded products and also more excellent in a balance between these properties than those given by conventional polyamide compositions. The present invention relates to a polyamide composition comprising polyamide, liquid-crystalline polyester, and non-liquid-crystalline polyester, characterized in that Ma part by mass of the polyamide, Mb part by mass of the liquid-crystalline polyester, and Mc part by mass of the non-liquid-crystalline polyester with respect to 100 parts by mass in total of the polyamide, the liquid-crystalline polyester, and the non-liquid-crystalline polyester satisfy the following formulas: 60?Ma?90, 2?Mb?38, and 2?Mc?Ma×0.2?2.

Abstract: Provided is an optical fiber including: a first core at a center thereof; a second core adjacent to the first core to cover a circumference of the first core; a third core adjacent to the second core to cover a circumference of the second core; and a cladding adjacent to the third core to cover a circumference of the third core, where conditions of 0.28%??1?0.4%, ?0.05%??2?0.05%, ?1.0%??3??0.5%, 3.8 ?m?a?4.5 ?m, 12 ?m?b?21 ?m, and 1.5 ?m?c-b?10 ?m hold, and loss increase resulting when the optical fiber is wound on a mandrel having a diameter of 20 mm is 0.

Abstract: A method for manufacturing a preform having a core and a multilayer clad, includes covering a circumference of a rod including at least the core and an inner clad layer with a first tube including at least a high viscosity clad layer, and unifying the rod and the first tube by heating and contracting the first tube.

Abstract: A glass base material, which is a base material of an optical fiber, comprising: a core; and a clad surrounding the core; wherein: a rate of change in a relative-refractive-index-difference between the core and the clad in a longitudinal direction of the glass base material is substantially 6% or less.

Abstract: The present invention can provide a polyamide composition that is more excellent in the heat resistance and tensile elongation of molded products and also more excellent in a balance between these properties than those given by conventional polyamide compositions. The present invention relates to a polyamide composition comprising polyamide, liquid-crystalline polyester, and non-liquid-crystalline polyester, characterized in that Ma part by mass of the polyamide, Mb part by mass of the liquid-crystalline polyester, and Mc part by mass of the non-liquid-crystalline polyester with respect to 100 parts by mass in total of the polyamide, the liquid-crystalline polyester, and the non-liquid-crystalline polyester satisfy the following formulas: 60?Ma?90, 2?Mb?38, and 2?Mc?Ma×0.2?2.

Abstract: A method for measuring non-circularity of a core portion of an optical fiber base material includes a distribution measuring step of (i) moving the optical fiber base material in a direction parallel to a central axis of the core portion while light is irradiated, in a direction perpendicular to the central axis, to the optical fiber base material which is immersed in the matching oil, and (ii) recording a variation in a width of a portion of the irradiated light which transmits through the core portion in association with a moved distance of the optical fiber base material, thereby measuring a distribution of relative values of an outer diameter of the core portion in terms of a longitudinal direction of the optical fiber base material, a distribution storing step of performing the distribution measuring step each time the optical fiber base material is rotated about the central axis by a predetermined angle, thereby recording a plurality of distributions of the relative values of the outer diameter of the c

Abstract: An optical fiber includes a clad portion and a core portion surrounded by the clad portion. Here, the clad portion is formed by substantially pure quartz, and the core portion has a higher refractive index than the clad portion. The optical fiber is characterized in that a relative refractive index difference of a center of the core portion falls within a range from 0.15% to 0.30%, and a maximum relative refractive index difference of the core portion falls within a range from 0.4% to 0.6%. Here, it is preferable that an average relative refractive index difference of the core portion falls within a range from 0.30% to 0.40%. Here, a mode field diameter of the optical fiber falls within a range from 8.6 ?m to 9.5 ?m at 1310 nm, and a cable cutoff wavelength of the optical fiber is equal to or lower than 1260 nm. Note that, after the optical fiber is subjected to hydrogen aging, a loss of the optical fiber is preferably equal to or lower than 0.4 dB/km at 1383 nm.

Abstract: A method for measuring non-circularity of a core portion of an optical fiber base material includes a distribution measuring step of (i) moving the optical fiber base material in a direction parallel to a central axis of the core portion while light is irradiated, in a direction perpendicular to the central axis, to the optical fiber base material which is immersed in the matching oil, and (ii) recording a variation in a width of a portion of the irradiated light which transmits through the core portion in association with a moved distance of the optical fiber base material, thereby measuring a distribution of relative values of an outer diameter of the core portion in terms of a longitudinal direction of the optical fiber base material, a distribution storing step of performing the distribution measuring step each time the optical fiber base material is rotated about the central axis by a predetermined angle, thereby recording a plurality of distributions of the relative values of the outer diameter of the c

Abstract: There is provided a packaging method of an optical fiber capable of performing a heavy hydrogen treatment during packing and storing easily and at low cost without a conventional grand processing apparatus. The packaging method includes: receiving an optical fiber 1 wound on an optical fiber bobbin 5 within a packing material 2 having flexibility to seal an opening part, sealing up the packing material 2 after introducing heavy hydrogen, and performing a heavy hydrogen treatment on the optical fiber 1 in a mixed gas atmosphere containing heavy hydrogen and air during storing and transporting the optical fiber 1. At this time, concentration of heavy hydrogen within the packing material 2 just after enclosing heavy hydrogen is within a range of 0.5 ppm to 4%. The opening part 3 of the packing material 2 may be sealed with heat or an adhesive after receiving the optical fiber 1, or may be sealed with a zipper.

Abstract: An optical fiber includes a clad portion and a core portion surrounded by the clad portion. Here, the clad portion is formed by substantially pure quartz, and the core portion has a higher refractive index than the clad portion. The optical fiber is characterized in that a relative refractive index difference of a center of the core portion falls within a range from 0.15% to 0.30%, and a maximum relative refractive index difference of the core portion falls within a range from 0.4% to 0.6%. Here, it is preferable that an average relative refractive index difference of the core portion falls within a range from 0.30% to 0.40%. Here, a mode field diameter of the optical fiber falls within a range from 8.6 ?m to 9.5 ?m at 1310 nm, and a cable cutoff wavelength of the optical fiber is equal to or lower than 1260 nm. Note that, after the optical fiber is subjected to hydrogen aging, a loss of the optical fiber is preferably equal to or lower than 0.4 dB/km at 1383 nm.

Abstract: There are provided an optical fiber processing apparatus, a processing method, and an optical fiber capable of monitoring a process of an optical fiber by gas containing at least deuterium and simultaneously detecting the termination of the process. The apparatus for processing an optical fiber in a gas atmosphere includes a door of a treatment container that puts the optical fiber in and out, a gas introducing port, a gas exhausting port, and a sampling fiber taking-out port. Further, the apparatus includes a light source that is connected to the optical fiber drawn from the sampling fiber taking-out port, and a light power meter that measures an absorption loss. In order to judge the termination of the gas process, it is preferable to include mechanism that monitors a value of the light power meter and judges the termination from the change of the value.

Abstract: In respect of a method for manufacturing a preform of an optical fiber, the method comprises the steps of forming a porous glass preform by accumulating glass particles, preparing a container made of a quartz glass, which is formed by heating the quartz glass with an electric furnace, providing a dehydration gas and an inert gas to the container, heating the container to which dehydration gas and inert gas is provided and dehydrating and sintering the porous glass preform by inserting the porous glass preform into the container, which is heated.

Abstract: A glass base material, which is a base material of an optical fiber, comprising: a core; and a clad surrounding the core; wherein: a rate of change in a relative-refractive-index-difference between the core and the clad in a longitudinal direction of the glass base material is substantially 6% or less.

Abstract: Even if an optical fiber obtained by drawing a preform is exposed to hydrogen atmosphere, an OH peak in the optical fiber at wavelength of about 1385 nm hardly rises regardless of the condition of drawing.