Sumitomo Electric Industries, Limited

Hirotaka Sakuma

Yoshiaki Tamura

Keisei Morita

Masato Suzuki

Tetsuya Hayashi

Takemi Hasegawa

Masaaki Hirano

Tetsuya Haruna

Shigehiro Nagano

Akiko Funakoshi

Takahiro Suganuma

A method for manufacturing an optical fiber preform made of silica-based glass, the method including: forming a core portion; and forming a cladding portion surrounding the core portion, the cladding portion having a refractive index lower than a refractive index of the core portion, wherein the forming the core portion includes: adding an alkali element group consisting of an alkali metal element and an alkaline earth metal element to an inner surface of a glass pipe made of silica-based glass; and integrating the glass pipe and a glass rod disposed inside the glass pipe to form an integrated rod after the adding.

Production method for optical fiber base material, and optical fiber base material

A multicore optical fiber of an embodiment has a structure for simultaneously realizing low transmission loss, low fusion splicing loss, and low inter-core crosstalk. The multicore optical fiber includes a plurality of cores comprised of silica glass, a common cladding comprised of silica glass and surrounding the plurality of cores, and a resin coating surrounding the common cladding. The common cladding has a refractive index lower than a refractive index of the plurality of cores. Each of the plurality of cores contains chlorine at 10000 ppm or more in at least part thereof.

Multicore optical fiber

A method for manufacturing an optical fiber preform includes: adding an alkali metal element or an alkaline earth metal element to an inner surface of a glass pipe made of silica-based glass; reducing a diameter of the glass pipe after the adding; etching an inner surface of a continuous section of the glass pipe in a longitudinal direction after the reducing; and collapsing the glass pipe after the etching. At least one of the adding, the reducing, the etching, and the collapsing includes performing a local etching on an inner surface of a section of the glass pipe that is shorter than the continuous section.

Method for producing optical fiber base material, and optical fiber base material

An optical fiber is formed from silica-based glass. The optical fiber includes a core including a central axis and a cladding surrounding the core. A refractive index of the core is greater than a refractive index of the cladding. The core contains chlorine, and one or more kinds of elements selected from an element group consisting of alkali metal elements and alkaline earth metal elements. A relative refractive index difference of the core based on a refractive index of pure silica is 0.00% or greater and 0.15% or less. An average concentration of fluorine in the cladding is 1.2% or less in a mass fraction.

Optical fiber

An optical fiber includes a core, and a cladding. When a refractive index of silica glass is set as n, a refractive index of the core is set as n, and a refractive index of the cladding is set as n, a relative refractive index difference Δ defined by Expression (1):Δ[%]=100×()/2  (1)is 0.2% or higher. A ratio of a maximum value of a concentration of the dopant composed of the alkali metal element or the alkaline-earth metal element in the cladding to a maximum value of a concentration of the dopant composed of the alkali metal element or the alkaline-earth metal element in the core is 0.06 or higher and 0.25 or lower.

An optical fiber according to an embodiment has a structure capable of reducing an increase in transmission loss. The optical fiber includes a glass part extending in a direction of a central axis, and the glass part is comprised of silica-based glass, includes a core and a cladding, and has residual stress approximately uniform throughout a cross section of the glass part orthogonal to the central axis, the core having the central axis and being doped with chlorine with a mass fraction of 1% or more, the cladding surrounding the core and having a refractive index lower than a maximum refractive index of the core.

One embodiment of the present disclosure relates to an optical fiber having lower transmission loss. The optical fiber is an optical fiber comprised of silica-based glass and includes a core including a central axis and a cladding. The cladding surrounds the core and has a refractive index lower than a refractive index of the core. The core contains phosphorus, chlorine, and fluorine. The core further includes an alkali metal element or an alkaline earth metal element. In a cross section of the optical fiber orthogonal to the central axis, a ratio Rp/Ra of a radius Rp of a phosphorus-containing region with respect to a radius Ra of the core is 0.3 or more.

An optical fiber has a structure uniform in a longitudinal direction. This optical fiber includes a core and a cladding that surrounds the core in a cross-section perpendicular to the longitudinal direction. A refractive index of the cladding is lower than a refractive index of the core. The cladding has, in the cross-section, an inner cladding layer including an inner circumferential surface of the cladding, and an outer cladding layer including an outer circumferential surface of the cladding. The inner cladding layer contains fluorine. The inner and outer cladding layers have refractive indexes different from each other. The outer cladding layer includes a local maximum portion where a residual stress, which is a tensile stress, becomes local maximum. A radial distance between the local maximum portion and an inner circumferential surface of the outer cladding layer is 10 &#x3bc;m or less.

An optical amplifier is provided in which adjacent ones of a plurality of cores each containing a rare-earth element and included in an amplifying multi-core optical fiber (MCF) serve as coupled cores at an amplifying wavelength, a connecting MCF is connected to the amplifying MCF, a pump light source is connected to the connecting MCF, and the pump light source pumps the rare-earth element in the amplifying MCF through the connecting MCF.

Optical amplifier and multi-core optical fiber

The present embodiment relates to an optical amplifier and the like having a structure for enabling efficient use of pumping light while avoiding complication of a device structure. In such an optical amplifier, since pumping light from a pumping light source is supplied to each core of an amplification MCF, a coupling MCF in which adjacent cores form a coupled core is arranged between the amplification MCF and the pumping light source. The pumping light source is optically connected to a specific core of the coupling MCF, and pumping light is coupled from the specific core to remaining cores except the specific core in the coupling MCF before pumping light is supplied to each core of the amplification MCF. This enables coupling of pumping light between optically connected cores between the amplification MCF and the coupling MCF.

An optical fiber having an effective area that can be easily increased and bending loss characteristics that can be easily improved is provided. The optical fiber includes a glass fiber including a core and a cladding; a first resin coating layer that is in contact with the glass fiber and surrounds the glass fiber; and a second resin coating layer that surrounds the first resin coating layer and has a Young's modulus greater than a Young's modulus of the first resin coating layer. An effective area is greater than or equal to 110 &#x3bc;mand less than or equal to 180 &#x3bc;mat a wavelength of 1550 nm. A cable cut-off wavelength is less than or equal to 1530 nm. A uniformity of thickness of the first resin coating layer is greater than or equal to 60% and less than or equal to 80%.

Optical fiber, colored optical fiber, and optical transmission system

An optical fiber is formed from silica glass, and includes a core, a first cladding which surrounds the core and has a refractive index lower than the refractive index of the core, and a second cladding which surrounds the first cladding and has a refractive index that is lower than the refractive index of the core and higher than the refractive index of the first cladding. The second cladding is divided into an inner region that is in contact with the first cladding and an outer region which surrounds the inner region and has a thickness that is half the thickness of the second cladding or less, while being 5 &#x3bc;m or more. The residual stress in at least a part of the outer region is a compressive stress.

The optical fiber offered is capable of not only restraining the attenuation due to glass defects, but also reducing the increase of manufacturing cost. The optical fiber is made of silica glass and includes a core and a cladding. The cladding encloses the core and has a refractive index smaller than that of the core. When the core is divided into inner core and outer core at half of the radius of the core, the average chlorine concentration of the inner core is larger than that of the outer core. The core includes any of the alkali metal group.

The optical fiber has an effective area that is greater than or equal to 110 &#x3bc;mand less than or equal to 180 &#x3bc;mat a wavelength of 1550 nm and a cable cut-off wavelength of less than or equal to 1530 nm. An average value of a glass outer diameter in a longitudinal direction is 125&#xb1;0.5 &#x3bc;m. When &#x3c3; is a standard deviation of the glass outer diameter in the longitudinal direction, 3&#x3c3; is greater than or equal to 0.1 &#x3bc;m and less than or equal to 0.5 &#x3bc;m.

Optical fiber, coated optical fiber, and optical transmission system

An optical fiber preform includes a silica-glass core portion, and a cladding portion surrounding the core portion, the cladding portion being composed of a fluorine-containing silica glass having a lower refractive index than the core portion, the core portion including a first region that does not include the central axis thereof, the first region containing a first dopant selected from sodium, potassium, and compounds thereof, and a second region that includes the central axis, the second region containing a second dopant that reduces the viscosity of the silica glass, the second dopant having a diffusion coefficient of 1&#xd7;10cm/s or more and less than the first dopant at 2,000&#xb0; C. to 2,300&#xb0; C., in which the entire core portion has an average first dopant concentration of 10 atomic ppm or more and 2,000 atomic ppm or less and an average second dopant concentration of 10 atomic ppm or more.

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Osaka, Japan

Hirotaka Sakuma