Sumitomo Electric Industries, Limited

Sumitomo Electric Optifrontier Co., Ltd.

Takemi Hasegawa

Eisuke Sasaoka

Masayuki Nishimura

Tetsuya Hayashi

Masashi Onishi

Yuki Kawaguchi

Yoshinori Yamamoto

Masato Suzuki

Yoshiaki Tamura

Shigehiro Nagano

Hirotaka Sakuma

Jun Kinugasa

Masaaki Hirano

Shinji Ishikawa

Manabu Shiozaki

Tomohiko Ueda

Toshifumi Hosoya

Daizo Nishioka

Tetsuya Nakanishi

Akira Inoue

Hiroshi Kohda

Hitoshi Hatayama

Ryo Yamaguchi

Koji Nakazato

Keisei Morita

Haruo Nakaji

Kiyotaka Murashima

Eiichiro Yamada

Mitsuharu Hirano

Keiichiro Fukuda

Masaharu Mogi

Suguru Takasaki

Saori Kubara

Takahiro Suganuma

Kazuaki Masui

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 gain flattening filter includes a first optical fiber that has a core, a first cladding, and a second cladding and that has a uniform composition in a length direction; and a pair of second optical fibers fused to both ends of the first optical fiber. The first optical fiber has a first section in which a slanted refractive index grating is formed and a pair of second sections connecting both ends of the first section to the pair of second optical fibers. The first cladding contains a photosensitive material whose refractive index increases upon irradiation with light having a specific wavelength. In the core, a tensile stress remains in the first section. An average MFD of the second sections is larger than an average MFD of the second optical fibers and smaller than an average MFD of the first section.

Gain flattening filter, and method for manufacturing gain flattening filter

An optical fiber has a central axis. The optical fiber includes a core made of silica glass and extending along the central axis, a cladding made of silica glass and surrounding the core, the cladding extending along the central axis, and a coating layer made of resin and surrounding the cladding, the coating layer extending along the central axis. An outer diameter of the cladding varies along the central axis. A residual stress in a direction along the central axis varies along the central axis, the residual stress being averaged over the core and the cladding in a cross section perpendicular to the central axis. A deviation from an average value of the outer diameter and a deviation from an average value of the residual stress have signs opposite to each other.

Optical fiber and method for producing optical fiber

The present disclosure relates to an optical fiber or the like that can be adapted to an optical transceiver for a short wavelength band of 850 nm or more and 1060 nm or less while maintaining compatibility with an SMF of the related art. An optical fiber of one embodiment includes a core, a cladding, and a resin coating, and has a mode field diameter of 8.2 &#x3bc;m or more and 9.6 &#x3bc;m or less at a wavelength of 1310 nm, a cable cutoff wavelength of an LP11 mode of 1060 nm or more and 1260 nm or less, and a cable cutoff wavelength of an LP02 mode of 1060 nm or less.

Optical fiber and optical cable

An optical fiber includes a core, an inner cladding surrounding the core, and an outer cladding surrounding the inner cladding. A mean relative refractive index difference &#x394;1 of the core, a mean relative refractive index difference &#x394;2 of the inner cladding, and a mean relative refractive index difference &#x394;3 of the outer cladding satisfy a relationship of &#x394;1&#x3e;&#x394;3&#x2265;&#x394;2. A ratio r2/r1 of an inner cladding radius r2 to a core radius r1 is 4.5 or higher and 5.5 or lower. A minimum value &#x394;min of a relative refractive index difference is &#x2212;0.030% or higher and &#x2212;0.010% or lower. A radius rmin at which the relative refractive index difference is the minimum value &#x394;min satisfies a relationship of r1&#x3c;rmin&#x3c;r2. (&#x394;min&#x2212;&#x394;(r1))/(rmin&#x2212;r1) is &#x2212;0.002%/&#x3bc;m or lower, where &#x394;(r1) denotes the relative refractive index difference with the core radius r1.

Optical fiber

A mode-dependent loss measurement device measures a mode-dependent loss of a measurement target optical fiber including a coupled MCF. The device includes a light source, a light receiver, a mode coupled state changer, and an analysis unit. The light source inputs light to an input end of an excitation optical fiber including another coupled MCF. The light receiver detects a sum of powers of outputted light beams from a plurality of core end faces positioned on an output end of the measurement target optical fiber. The mode coupled state changer changes a mode coupled state of the excitation optical fiber. The analysis unit obtains a mode-dependent loss of the measurement target optical fiber from variations in optical powers detected by the light receiver.

Mode-dependent loss measurement device and mode-dependent loss measuring method

An optical fiber line of one embodiment comprises an HNLF, an SMF, and an MFD transition portion. The MFD transition portion includes end portions of both the HNLF and the SMF facing with a fusion point thereof, and is a section in which an MFD changes such that a difference between a maximum value and a minimum value is 0.3 &#x3bc;m or more for a 100 &#x3bc;m-length. A splicing loss of the HNLF and the SMF at 1,550 nm is one-fifth or less than an ideal butting loss at stationary portions thereof. A total length of the MFD transition portion is 10 mm or less. In a region between one end surface of the HNLF at the fusion point and the other end surface separated from the one end surface by 50 &#x3bc;m or more and 300 &#x3bc;m or less, the MFD increases monotonically from the other end surface to the one end surface.

Optical fiber line, module, and method for manufacturing optical fiber line

An optical fiber according to an embodiment includes a core, a cladding, and a coating layer. At the boundary between the core and the cladding, the local sound velocity decreases in the direction from the core side toward the cladding side. At least in the cladding, the local sound velocity changes continuously in a radial direction. Further, the line width of the Brillouin gain of the light beam guided by the fundamental mode is 60 MHz or more.

One embodiment of the present disclosure relates to an SFG (slanted fiber grating) that can easily realize a high-performance gain equalizer. The SFG includes an optical fiber comprised of silica-based glass and including a core, a first cladding containing a photosensitive material, and a second cladding. A specific section between two different points arranged along a fiber axis in the optical fiber is configured with a first region, a pair of second regions, and a third region. The first region includes a slanted Bragg grating provided in a region as the first cladding. The pair of second regions are arranged to sandwich the first region. The third region is disposed to sandwich both the first region and the pair of second regions. An MFD at a wavelength of 1.55 &#x3bc;m in the third region is smaller than an MFD at a wavelength of 1.55 &#x3bc;m in the first region.

Slant-type fiber grating

An optical fiber according to an embodiment includes a core and a cladding. The average value n1_ave of the refractive index of the core, the minimum value nc_min of the refractive index of the cladding, and the refractive index n0 of pure silica glass satisfy relationships of n1_ave&#x3e;nc_min and nc_min&#x3c;n0. The cladding contains fluorine. The fluorine concentration in the cladding is adjusted to be minimum in the outermost portion of the cladding including the outer peripheral surface of the cladding.

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.

The present invention relates to a method and device for measuring optical nonlinearity of an optical fiber to be measured comprising a plurality of cores having mutually coupled waveguide modes. The method includes, at least, preparing a laser light source emitting laser light and a detecting unit determining an optical intensity, inputting laser light into a specific core of the optical fiber to be measured, determining the intensity of a specific wavelength component caused by optical nonlinearity among the reflective light components from the optical fiber to be measured, and determining optical nonlinearity of the optical fiber to be measured on the basis of the intensity of the specific wavelength component.

Nonlinearity measuring method and nonlinearity measuring device

An optical fiber includes a core and a cladding. The core contains silica glass and includes a central portion (part having a diameter of 0.5 &#x3bc;m or more and 4 &#x3bc;m or less). The central portion has the central axis of the optical fiber. The cladding contains silica glass and surrounds the core. The core contains chlorine. A chlorine concentration averaged in the entire core is 10,000 ppm or more and 50,000 ppm or less. The chlorine concentration averaged in the entire core minus a chlorine concentration averaged in the central portion is 4,500 ppm or more and 13,500 ppm or less.

An optical fiber according to an embodiment includes: a core; an inner cladding surrounding the core and having a refractive index smaller than a refractive index of the core; an outer cladding surrounding the inner cladding and having a smaller refractive index than the refractive index of the core and having a refractive index greater than the refractive index of the inner cladding, in which a ratio of a caustic radius to a MAC-value (caustic radius/MAC-value) at a bending radius of 10 mm at a wavelength of 1625 nm is 2.70 &#x3bc;m or more.

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Yokohama, Japan

Takemi Hasegawa