Abstract: A method for manufacturing a base material for an optical fiber, includes steps of: holding a bar material by a support member; and adjusting to reduce a difference between an axis of the bar material and a rotational axis of the support member. Furthermore, an optical fiber base material grasping apparatus for holding a bar material having an axis, includes: a support member having a center axis, the support member being rotatable around the center axis; and an adjusting mechanism for reducing a difference between the axis of the bar material and the central axis of the support member.

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: 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: A method for manufacturing a glass base material for an optical fiber by forming a core rod having a core section and a portion of a clad, forming an additional clad by depositing glass particles on circumference of the core rod, and performing a sintering and vitrifying process on an obtained porous base material, includes the step of forming the core rod in order that the relation 3.75≦a/m≦6 is satisfied, where ‘a’ denotes an outer diameter of a section corresponding to the core rod, and ‘m’ denotes a mode field diameter at 1385 nm in wavelength with regard to the optical fiber obtained by drawing the glass base material.

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 provides a polyamide resin composition which contains: (A) 30 to 70 parts by weight of a polyamide resin; (B) 70 to 30 parts by weight of an inorganic filler; and (C) carbon black in an amount of 0.05 to 10 parts by weight per 100 parts by weight of the sum of components (A) and (B), wherein the inorganic filler (B) contains (b1) glass fiber, and (b2) at least one species selected from the group consisting of wollastonite, talc, kaolin and mica; the carbon black (C) has an average primary particle size of 20 nm or less and an average aggregate size of 50 to 120 nm. Also disclosed is a molded article obtained from the polyamide resin composition.

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.

Abstract: A method for manufacturing a base material of optical fibres having a desired ratio of core to clad, including forming a porous base material upon depositing glass particles, producing a core member upon dehydrating and vitrifying the porous base material, adding a clad member onto the core member, is characterized in that the method includes, a step of dehydrating the porous base material in an atmosphere of gas including helium and chlorine within an electric furnace; a step of vitrifying the porous base material in an atmosphere of inert gas including helium; and a step of providing a purging step of heating the porous base material in an atmosphere of inert gas mainly including helium between the dehydrating step and the vitrifying step.

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 method for manufacturing a preform, which is a base material of an optical fiber, comprising: forming porous-glass-base-material by accumulating glass particles; dehydrating the porous-glass-base-material by heating the porous-glass-base-material in an atmosphere of gas that contains chlorine; heating the porous-glass-base-material dehydrated by the dehydrating with a first heating temperature in an atmosphere of a first inert gas; and vitrifying the porous-glass-base-material by heating the porous-glass-base-material with a second heating temperature in an atmosphere of second inert gas.

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: A glass fiber reinforced polyamide resin composition comprising: (A) a polyamide resin; and, per 100 parts by weight thereof, (B) from 20 to 170 parts by weight of glass fibers; (C) from 0.01 to 5 parts by weight of a higher fatty acid amide compound; and (D) from 0.005 to 5 parts by weight of a higher fatty acid metal salt having an acid value of 0.5 mg KOH/g or less. The composition preferably further comprises (E) from 0.01 to 5 parts by weight of an azine dye per 100 parts by weight of a polyamide resin (A). Also disclosed is a molded article obtained from the composition.

Abstract: A method for manufacturing a base material for an optical fiber, includes steps of: holding a bar material by a support member; and adjusting to reduce a difference between an axis of the bar material and a rotational axis of the support member. Furthermore, an optical fiber base material grasping apparatus for holding a bar material having an axis, includes: a support member having a center axis, the support member being rotatable around the center axis; and an adjusting mechanism for reducing a difference between the axis of the bar material and the central axis of the support member.

Abstract: A glass fiber reinforced polyamide resin composition comprising: (A) a polyamide resin; and, per 100 parts by weight thereof, (B) from 20 to 170 parts by weight of glass fibers; (C) from 0.01 to 5 parts by weight of a higher fatty acid amide compound; and (D) from 0.005 to 5 parts by weight of a higher fatty acid metal salt having an acid value of 0.5 mg KOH/g or less. The composition preferably further comprises (E) from 0.01 to 5 parts by weight of an azine dye per 100 parts by weight of a polyamide resin (A). Also disclosed is a molded article obtained from the composition.

Abstract: Proposed is an improvement in the VAD process for the preparation of a porous silica glass preform for double-core optical fibers by using three oxyhydrogen flame burners installed one above the other in a flame hydrolysis chamber in which a porous silica glass body consisting of the center core portion formed by the lowermost burner, side core portion formed by the middle burner and the cladding layer formed by the uppermost burner is gradually pulled up as it grows under rotation. Different from conventional procedures in which the extension of the nozzle axis of each of the burners intersects with the rotation axis of the growing body, the extension of the nozzle axis of the middle burner for the side core is displaced in a horizontal direction by a limited distance not to intersect nor to be in parallel with the rotation axis in the invention. By this means, an improvement is obtained in the uniformity of distribution of the refractive index in the side core which otherwise is remarkably disordered.

Abstract: An improvement is proposed, in a method for the preparation of a step-index silica glass preform as a precursor of optical fibers by completing the cladding layer of the secondary preform by the outer deposition on and around a primary preform consisting of the center core and side core, to conduct the outer deposition for the cladding layer in such a way that the inequality.vertline.d.lambda..sub.0 /dk.vertline..ltoreq.500 nmis satisfied, in which k is the ratio of the diameter of the primary preform to the diameter of the secondary preform and .lambda..sub.0 is the zero-dispersion wavelength in nm of an optical fiber obtained by drawing the secondary preform, d.lambda..sub.0 /dk being the differential of a function held between .lambda..sub.0 and k determined beforehand from the distribution of the refractive index within the primary preform.