Fujikura Limited

Osaka Prefecture University Public Corporation

Shimane University

Ryo Maruyama

Shoichiro Matsuo

Nobuo Kuwaki

Kenji Yamashiro

Masaharu Ohashi

Takayuki Kitamura

Shunichirou Hirafune

Tatsuya Kishi

Sho Endo

Katsubumi Nagasu

Fumihiko Ito

An optical fiber includes a glass portion, a primary coating layer, and a secondary coating layer. In the optical fiber, a value of microbend loss characteristic factor Fis 6.1 ([GPa·μm/rad]·10) or less when represented by,where Fis geometry microbend loss characteristic and Fis optical microbend loss characteristic.

Optical fiber

An optical fiber includes a glass portion, a primary coating layer, and a secondary coating layer. In the optical fiber, a value of microbend loss characteristic factor Fis 6.1 ([GPa&#xb7;&#x3bc;m/rad) or less when represented by,where Fis geometry microbend loss characteristic and Fis optical microbend loss characteristic.

An optical fiber includes a glass portion, a primary coating layer, and a secondary coating layer. In the optical fiber, a value of microbend loss characteristic factor Fis 2.6 ([GPa&#xb7;&#x3bc;m&#xb7;dB/turn]&#xb7;10) or less, when represented byby using geometry microbend loss characteristic Fand optical microbend loss characteristic F.

An optical fiber includes: a core; a depressed layer surrounding the core; and a cladding surrounding the depressed layer. A refractive index profile of the core is an &#x3b1;-th power distribution having an index &#x3b1; of 1.0 or more and 2.9 or less. A relative refractive index difference &#x394;of the depressed layer with respect to the cladding has an absolute value |&#x394;| that is 0.05% or more and 0.15% or less. A ratio r1/r2 of a radius r1 of the core to an outer radius r2 of the depressed layer is 0.35 or more and 0.60 or less. A cable cutoff wavelength &#x3bb;cc of 22 m is less than 1.26 &#x3bc;m. A mode field diameter at a wavelength of 1.31 inn is larger than 8.6 inn and smaller than 9.5 &#x3bc;m.

A measurement method for measuring an effective refractive index difference between two propagation modes of a multimode fiber is provided. The method includes: measuring a first Brillouin frequency shift &#x3bd;by specifying a frequency having a lowest-frequency peak out of peaks in a first frequency spectrum of scattered light in a first propagation mode; measuring a second Brillouin frequency shift &#x3bd;by specifying a frequency having a lowest-frequency peak out of peaks in a second frequency spectrum of scattered light in a second propagation mode; and calculating an effective refractive index difference &#x394;nin accordance with &#x394;n=(&#x3bd;)/(2kV) with use of the first Brillouin frequency shift &#x3bd;, the second Brillouin frequency shift &#x3bd;, a predetermined wave number k of light in a vacuum, and a predetermined constant V.

Measurement method, measurement device, and non-transitory recording medium

An optical fiber includes: a core; a cladding layer that is lower in refractive index than the core; and a depressed layer that lies between the core and the cladding layer and that is lower in refractive index than the cladding layer, wherein: the optical fiber has an effective core area Aeff that is equal to or greater than 100 &#x3bc;mand equal to or less than 129 &#x3bc;m, the core has a radius r1 that is equal to or greater than 5.2 &#x3bc;m and equal to or less than 7.4 &#x3bc;m, the core has a refractive index volume Vcore that is equal to or greater than 8.5% &#x3bc;mand equal to or less than 16.5% &#x3bc;m, the depressed layer has a refractive index volume Vdep that is equal to or greater than &#x2212;40% &#x3bc;mand less than 0% &#x3bc;m.

Optical fiber and method for manufacturing same

An optical fiber includes a core, a depressed layer surrounding the core, and a cladding surrounding the depressed layer, where a refractive index profile of the core is an &#x3b1; power distribution in which an index &#x3b1; is 3 or more and 6 or less, a relative refractive index difference &#x394;of the depressed layer with respect to the adding is set such that an absolute value |&#x394;| thereof is 0.01% or more and 0.05% or less, a radius r1 of the core and an outer circumference radius r2 of the depressed layer are set such that a ratio r1/r2 thereof is 0.2 or more and 0.5 or less, a cable cutoff wavelength &#x3bb;of 22 m is 1260 nm or less, and a mode field diameter MFD at a wavelength of 1310 nm is 8.6 &#x3bc;m or more and 9.5 &#x3bc;m or less.

Optical fiber and method of manufacturing the same

An optical fiber includes a core, a depressed inner cladding surrounding the core, and an outer cladding surrounding the inner cladding, where a refractive index profile of the core includes an &#x3b1; power distribution in which an index &#x3b1; is 3.5 or more and 6 or less, a relative refractive index difference &#x394;of the inner cladding with respect to the adding is set such that an absolute value |&#x394;| thereof is 0.01% or more and 0.045% or less, a radius r1 of the core and an outer circumference radius r2 of the inner cladding are set such that a ratio r1/r2 thereof is 0.2 or more and 0.6 or less, a cable cutoff wavelength &#x3bb;of 22 m is 1260 nm or less, and a mode field diameter MFD at a wavelength of 1310 nm is 8.6 &#x3bc;m or more and 9.5 &#x3bc;m or less.

An optical fiber includes: a core; and a clad which is formed so as to surround an outer circumference of the core concentrically with the core, the clad having at least an inner cladding layer adjacent to the outer circumference of the core and an outer cladding layer formed on an outer circumference of the inner cladding layer, wherein a refractive index of the outer cladding layer is &#x394;, and an outer circumference radius of the outer cladding layer is r, a relationship of &#x394;max&#x3e;&#x394;min is satisfied, a relationship of &#x394;min&#x2264;0.08% is satisfied, a relationship of r&#x3c;r&#x3c;ris satisfied, a relationship of 0.35&#x2264;r/r&#x2264;0.55 is satisfied, a cable cut-off wavelength is less than or equal to 1260 nm, and an MFD at a wavelength of 1310 nm is 8.6 &#x3bc;m to 9.2 &#x3bc;m.

An optical fiber including a core and a cladding including an inner cladding layer and an outer cladding layer is provided. The refractive index of the core &#x394;1, the refractive index of the inner cladding layer &#x394;2, and the refractive index of the outer cladding layer &#x394;3 have a relationship denoted by the following expressions: &#x394;1max&#x3e;&#x394;2min and &#x394;1max&#x3e;&#x394;3, and 0.01%&#x3c;|&#x394;2min&#x2212;&#x394;3|&#x3c;0.03%. An outer circumference radius r1 of the core, an outer circumferential radius r2 of the inner cladding layer, and an outer circumferential radius r3 of the outer cladding layer have a relationship denoted by the following expressions: r1&#x3c;r2&#x3c;r3, and 0.2&#x2266;r1/r2&#x2266;0.5. A cable cut-off wavelength &#x3bb;cc 1260 nm or less. A mode field diameter at a wavelength of 1310 nm is 8.6 &#x3bc;m or more and 9.5 &#x3bc;m or less.

Optical fibers Fp, Fn, included in a light transmission path, are two-mode optical fibers for propagating an LP01 mode component and an LP11 mode component contained in signal light, and a gradient d&#x394;&#x3c4;/d&#x3bb; of a mode dispersion &#x394;&#x3c4; with respect to a wavelength &#x3bb; in a wavelength band of 1530 nm to 1625 nm is |0.5| ps/km/nm or less. Symbols of mode dispersions &#x394;&#x3c4; of the optical fibers Fp, Fn are opposite to each other. The light transmission path can satisfactorily compensate the mode dispersion in a wide wavelength band.

Two-mode optical fiber and light transmission path

An optical fiber, including (i) an inner core having an &#x3b1;-power refractive index profile, (ii) an outer core having a refractive index of n1', and (iii) a cladding having a refractive index of n2 (n1&#x2032;&#x3c;n2&#x3c;n1), is configured such that a depth of a trench, defined by n2&#x2212;n1&#x2032;, is sufficiently increased.

Optical fiber and optical transmission line

An optical fiber () includes (i) an inner core () whose refractive index distribution has an &#x3b1; profile, (ii) an outer core () which surrounds the inner core (), and (iii) a clad () which surrounds the outer core (). In the optical fiber (), Rd is set to not less than 0.15, where Rd is a ratio of a refractive index difference between the outer core () and the clad () to a refractive index difference between a center part of the inner core () and the clad ().

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Sakura, Japan

Ryo Maruyama