Shin-etsu Chemical Co., Ltd.

Yuhei Urata

Makoto Yoshida

Hiroshi Oyamada

Hiroki Kojima

Yuichi Matsunaga

A method of measuring a diameter of a core portion of an optical fiber preform including the core portion having a relatively high refractive index and a clad portion having a relatively low refractive index. The method includes applying parallel light to the optical fiber preform, and measuring the diameter of the core portion from an image captured by receiving the light having transmitted through the optical fiber preform.

Method of measuring optical fiber preform

An optical fiber preform manufacturing apparatus comprising a seal member, wherein the seal member is attached to a flange portion formed in an open portion of a reaction chamber into which a burner is inserted, the seal member includes a first sheet that is flexible and includes an open portion that is smaller than an outer diameter of the burner, through which the burner is inserted; a second sheet having the same thickness as the first sheet and including an open portion that is larger than an outer diameter of the first sheet; and two third sheets that each include an open portion that is larger than the outer diameter of the burner and smaller than the outer diameter of the first sheet, the second sheet is arranged in the same plane as the first sheet, and the first and second sheets are sandwiched by the two third sheets.

Apparatus for manufacturing optical fiber preform

Provided is a method of manufacturing a porous glass deposition body for optical fiber comprising depositing silica powder on a starting member being raised and rotated by using burners with different deposition positions. With a glass raw material flow rate supplied to a core deposition burner represented by Fand a total flow rate of glass raw material supplied to a cladding deposition burner adjacent to the core deposition burner represented by F, during an initial deposition stage occurring before gas conditions reach a stable state, glass raw material is supplied to points at the same longitudinal position of the deposition body such that a glass raw material flow rate ratio F/Fis no less than 0.69 and no greater than 1.03.

Method of manufacturing porous glass deposition body for optical fiber

A method is provided for producing a glass fine particle deposit by a VAD method using a core deposition burner and a cladding deposition burner disposed adjacent to the core deposition burner. The cladding deposition burner including five cylindrical tubes having different outer diameters and concentrically superimposed on one another and a group of small-diameter nozzles arranged in a ring shape in a third region from the inner side. The method includes flowing, in the cladding deposition burner, a glass raw material gas and a combustion supporting gas in a first region from the inner side, air in a second region from the inner side, a combustible gas in the third region from the inner side, a combustion supporting gas in the group of small-diameter nozzles, an inert gas in a fourth region from the inner side, and a combustion supporting gas in a fifth region from the inner side, respectively.

Method for producing porous glass deposit for optical fiber

In a device for producing a large-sized porous base material by a VAD process, the cracking and variation of the outer diameter of the base material are suppressed by forming a smooth tapered part, without changing the length of a non-effective part. In producing the porous base material by a VAD process, the time for a gas to reach a flow amount of the gas in a steady state from starting of the deposition is extended more in a burner that deposits glass microparticles on a layer closer to the outside of the base material.

Method for producing porous glass base material

A glass fine particle synthesis burner comprising a glass raw material gas emission path for emitting glass raw material; a ring-shaped combustible gas emission path for emitting combustible gas arranged outside the glass raw material emission path; a ring-shaped combustion aiding gas emission path for emitting combustion aiding gas arranged outside the combustible gas emission path; and small diameter nozzles for emitting the combustion aiding gas within the combustible gas emission path. In a cross section of the glass fine particle synthesis burner formed by cleaving orthogonal to a central axis thereof, when the glass fine particle synthesis burner is divided into two regions by a predetermined straight line passing through a center of the glass fine particle synthesis burner, a total area of the small diameter nozzles in one of the regions is greater than a total area of the small diameter nozzles in the other region.

Glass fine particle synthesis burner, glass fine particle deposition body manufacturing method, and glass fine particle deposition apparatus

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%&#x2266;(&#x394;&#x2212;&#x394;)&#x2266;0.65%, 0.30%&#x2266;&#x394;&#x2266;0.55%, &#x2212;0.20%&#x2266;&#x394;&#x2266;&#x2212;0.05%, 0.22&#x2266;a/b&#x2266;0.34, and 4&#x2266;b&#x221a;|&#x394;|&#x2266;10 hold, and loss increase resulting when the optical fiber is wound on a mandrel having a diameter of 20 mm is 0.5 dB/turn or smaller at a wavelength of 1550 nm, where &#x394;(%) is a specific refractive index difference of a maximum of a refractive index distribution of the core with reference to a refractive index of the second cladding, &#x394;(%) is a specific refractive index difference of a minimum of a refractive index distribution of the first cladding with reference to the refractive index of the second cladding, a(&#x3bc;m) is a radius of a boundary between the core and the first cladding with respect to a center of the core, and b(&#x3bc;m) is a radius of a boundary between the first cladding and the second cladding with respect to the center of the core.

Growing community of inventors

Ibaraki, Japan

Yuhei Urata