Hokkaido University

Fujikura Limited

Sumitomo Electric Industries, Limited

Nippon Telegraph and Telephone Corporation

Clemson University

Technical University of Denmark

Kunimasa Saitoh

Katsuhiro Takenaga

Yusuke Sasaki

Shoichiro Matsuo

Hitoshi Uemura

Masanori Koshiba

Takeshi Fujisawa

Shoji Tanigawa

Masahiro Kashiwagi

Shota Saito

Yoshimichi Amma

Liang Dong

Kazuhide Nakajima

Takashi Matsui

Taiji Sakamoto

Kentaro Ichii

Koji Omichi

Naoki Fujiwara

Kyozo Tsujikawa

Takuo Hiratani

Toshio Morioka

Katsuhiro Takenage

Shioichiro Matsuo

Takanori Sato

Takenaga Katsuhiro

Kashiwagi Masahiro

Tanigawa Shoji

An optical filter includes a first loop mirror, a second loop mirror, a first waveguide optically coupled to the first loop mirror and the second loop mirror, a second waveguide optically coupled to the first loop mirror and the second loop mirror, a first access waveguide optically coupled to the first waveguide, a second access waveguide optically coupled to the second waveguide, and an output section, wherein the first loop mirror includes a first loop waveguide and a first multiplexer/demultiplexer, the second loop mirror includes a second loop waveguide and a second multiplexer/demultiplexer, the output section includes a third loop waveguide, a third multiplexer/demultiplexer, a third waveguide, and a fourth waveguide, the third loop waveguide optically coupled to the second loop waveguide and the third multiplexer/demultiplexer, the third waveguide and the fourth waveguide optically coupled to the third multiplexer/demultiplexer, and the output section.

Optical filter and wavelength tunable laser element

An object of the present invention is to provide a multi-core optical fiber that can prevent an increase in bending loss even when a distance between a peripheral core and a cladding boundary is decreased, and can improve a bending loss characteristic in a state where an influence on a cutoff wavelength and a mode field diameter is small, and a design method thereof. The multi-core optical fiber according to the present invention is an optical fiber in which two or more core regions are arranged in a cladding region having a refractive index lower than a refractive index of the core at a minimum core interval, a ring-shaped low refractive index region surrounding the core and having a refractive index lower than the refractive index of the cladding region is provided, a bending loss after the provision of the ring-shaped low refractive index region is reduced as compared with a characteristic in a case where the ring-shaped low refractive index region is not provided, and at the same time, a change in mode field diameter after the provision of the ring-shaped low refractive index region is not changed as compared with a characteristic in a case where the ring-shaped low refractive index region is not provided.

Multicore optical fiber and design method

A multicore fiber includes: a first core having a first propagation loss of a first light beam in a mode one order higher than a mode of a second light beam that transmits information. The first propagation loss is 0.02 dB/m or more and 1 dB/m or less, in a wavelength band of light beams including the second light beam that transmit the information when a bend having a diameter of 280 mm is applied to the multicore fiber.

Multicore fiber

A multicore fiber for communicationwhich allows propagation of an optical signal includes: a clad; a corewhich is arranged in a center of the clad; and seven to ten coreswhich are arranged at equal intervals surrounding the core, and the cladding diameter is 230 &#x3bc;m, distances between centers of the mutually neighboring coresandare 30 &#x3bc;m or more, distances between the centers of the coresand an outer peripheral surface of the cladare 35 &#x3bc;m or more and a mode field diameter of light propagating in the coresandis 9 &#x3bc;m to 13 &#x3bc;m.

Multicore fiber for communication

A multicore fiber that includes: three or more cores that transmit in single-mode transmission; a common clad that covers a periphery of the three or more cores; and a low-refractive index portion that has a refractive index lower than a refractive index of the clad. The multicore fiber further includes a region having the three or more cores arranged annularly on a cross-section perpendicular to a longitudinal direction. At least a portion of the low-refractive index portion is arranged inside a minimum inscribed circle of two adjacent cores within the region.

Multicore fiber and optical cable

A multi-core fiber performs communication using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multi-core fiber includes: a plurality of signal light propagation cores that propagate light up to an (x+1)th-order LP mode; and at least one high-loss core that has a higher loss of propagated light than the signal light propagation cores. Crosstalk occurs between light of the (x+1)th-order LP mode propagated through at least one signal light propagation core and light of a primary LP mode propagated through at least one high-loss core.

Multi-core fiber

A multicore fiber includes: a first core configured to propagate an LPmode, an LPmode, and an LPmode light beam; and a second core configured to propagate an LPmode light beam, wherein a different mode interaction section is provided in which a propagation constant of the LPmode light beam propagated through the first core is matched with a propagation constant of the LPmode light beam propagated through the second core, a different mode non-interaction section is provided in which propagation constants of the LP mode light beams propagated through the first core are not matched with propagation constants of the LP mode light beams propagated through the second core, and the first core includes an inner core and an outer core surrounding the inner core with no gap and having a refractive index higher than a refractive index of the inner core.

A multicore fiber communicates using light up to an xth-order LP mode (where x is an integer of 1 or more) in a communication band. The multicore fiber includes: a plurality of cores; a clad that surrounds the plurality of cores and has a refractive index lower than refractive indexes of the plurality of cores; and a cover layer that covers the clad and has a refractive index higher than the refractive index of the clad. Each of the plurality of cores propagates light up to an (x+1)th-order LP mode. A core pitch is set to a distance where crosstalk of the light up to the xth-order LP mode becomes less than or equal to &#x2212;40 dB/km and crosstalk of light of the (x+1)th-order LP mode becomes greater than or equal to &#x2212;30 dB/km.

A multicore fiber includes: a center core that propagates four LP mode light beams including an LPmode light beam; and a first to a fifth cores disposed on a first line to a fifth line segments extend from the center of the center core in the radial direction at predetermined angles. The multicore fiber includes a different mode interaction section in which the propagation constants of each mode light beam propagated through the center core are matched with the propagation constants of LPmode light beams propagated through the first to fifth cores.

A multicore fiber including two or more cores each capable of single mode transmission, a cladding covering around the two or more cores in common, and a low refractive index portion having a refractive index lower than a refractive index of the cladding, wherein a cross-section perpendicular to a longitudinal direction includes a region where two or more cores of a part or all of the two or more cores are arranged in a circular shape and at least a part of the low refractive index portion is arranged inside an inscribed circle of the cores included in the region.

No core is disposed at the lattice point of a triangular lattice of a first layer LY. First coresandof the core elementsandare disposed at the lattice points of a second layer LY. A first coreof the core elementand the second coreare alternately disposed at the lattice points of a third layer LY. In a fourth layer LY, no core is disposed at six lattice points, and the first coresandof the core elementsandare disposed at the other lattice points. The second coresare adjacent to the lattice points of the fourth layer LY, at which no core is disposed. The effective refractive indexes of the core elements adjacent to each other are different from each other.

A multicore fiberincludes: a small diameter portionin which a propagation constant of light of an x-th order LP mode of the first core(here, xis an integer of '2' or more and x or less, x is an integer of '2' or more) and a propagation constant of light of a y1-th order LP mode of the second core(here, yis an integer of &#x201c;1&#x201d; or more and y or less other than x, y is an integer of &#x201c;1&#x201d; or more) coincide with each other and a large diameter portion in which a propagation constant of light of each LP mode of the first coreand a propagation constant of light of each LP mode of the second coreare configured not to coincide with each other are arranged.

Multicore fiber with different-mode interaction section

In a C band and an L band, the effective refractive indices of light propagating through the coresandadjacent to each other are different from each other such that a magnitude of crosstalk of light of a highest-order LP mode commonly propagating through the coresandadjacent to each other between the coresandadjacent to each other becomes a peak at a bending diameter smaller than a diameter of 100 mm, and the core has a higher refractive index in a center portion than in an outer circumferential portion such that a differential mode group delay of the coresandis 700 picoseconds/km or less.

Growing community of inventors

Sapporo, Japan

Kunimasa Saitoh