Nippon Telegraph and Telephone Corporation

Fujikura Limited

Osaka Prefecture University Public Corporation

Shimane University

Toyama Gakki Seizo K.k.

University Public Corporation Osaka

National University Corporation Shimane University

Hirotaka Ono

Makoto Yamada

Yutaka Miyamoto

Shoichiro Matsuo

Katsuhiro Takenaga

Terutoshi Kanamori

Kentaro Ichii

Yasutake Ohishi

Atsushi Mori

Hiroji Masuda

Toshiyuki Shimada

Takayuki Mizuno

Shingo Kawai

Koki Shibahara

Mitsunori Fukutoku

Tsukasa Hosokawa

Kyouzou Tsujikawa

Kenya Suzuki

Keita Yamaguchi

Makoto Shimizu

Kazunori Senoo

An amplification fiber includes a core which is doped with an erbium ion and a cladding which surrounds the core and has a refractive index lower than a refractive index of the core, and a relative refractive index difference Δnbetween the core and the cladding is not more than a smaller one of values of a relative refractive index difference Δnexpressed as a predetermined expression related to a radius a of the core and a relative refractive index difference Δnexpressed as a predetermined expression related to the radius a of the core.

Amplifying fiber and optical amplifier

There is provided a multimode optical amplifier that provides gain to a plurality of propagation modes of signal light. The multimode optical amplifier includes a multiplexer that multiplexes the signal light and excitation light; an amplifying fiber which has a core that propagates a predetermined plurality of propagation modes of the signal light and a predetermined plurality of propagation modes of the excitation light, and which provides an individual gain value for each of the predetermined propagation modes of the signal light; a wavelength-flattening filter that maintains a constant gain value for a frequency for all predetermined propagation modes of the signal light; and a mode-flattening filter that maintains the gain value at a constant value for a predetermined propagation mode of the signal light for all predetermined propagation modes of the signal light.

Multimode optical amplifier

An optical repeater device includes an amplifier module and a monitoring control circuit. The optical amplifier module includes an amplifier optical circuit including a plurality of amplification cores that amplify signal light propagating through different cores, and an optical amplifier control circuit that receives detection results from optical detectors at a plurality of signal light waveguide points of the amplifier optical circuit and generates a control signal directed to an excitation light source. The monitoring control circuit includes a reception unit that receives monitoring control channel light, a transmission unit that transmits the monitoring control channel light, an information determination unit that determines whether the monitoring control information received from the reception unit is for its own device or for another device, and a monitoring control unit that receives monitoring control information from the other device via the reception unit and the information determination unit and transmits the monitoring control information of its own device to the other device via the transmission unit and the information determination unit.

Optical transponder

An optical repeater in a mode-division-multiplexing (MDM) optical transmission system prevents a signal-to-noise ratio (SNR) from deteriorating due to a loss of a mode demultiplexer. The optical repeater in the MDM optical transmission system is configured to include at least one multimode optical amplifier, a mode demultiplexer, a mode multiplexer, and variable optical attenuators. One of the multimode optical amplifiers is disposed on the input side of the mode demultiplexer.

Optical repeater

An optical node device includes one or more input-side wavelength selection switches, a plurality of output-side wavelength selection switches, and an amplification unit. The input-side wavelength selection switches include a plurality of output ports, separate input light in accordance with a wavelength, and output the separated light from the output port corresponding to an output destination of the separated light. The output-side wavelength selection switches include input ports each receiving the light output from each of the one or more input-side wavelength selection switches, multiplex the light received from the input ports, and output the light. The amplification unit amplifies the light output from each of the output ports of the input-side wavelength selection switches and outputs the amplified light to the output-side wavelength selection switch at the output destination corresponding to the output port.

Optical node device

An optical node device includes: a multicore optical amplification unit that amplifies collectively light transmitted along a multicore fiber; a separation unit that inputs the amplified light in each core to each of a plurality of input-side single-core fibers; an optical cross-connect switch that attenuates the light input from each of the plurality of input-side single-core fibers through an optical attenuator, separates the light in accordance with a wavelength, and outputs the separated light to an output-side single-core fiber of a plurality of output-side single-core fibers related to a respective output destination; a plurality of single-core optical amplification units that amplify the light transmitted along the corresponding output-side single-core fibers; and an output unit that outputs the light transmitted along each of the plurality of output-side single-core fibers to a multicore fiber. A control unit controls the optical attenuator and the single-core optical amplification unit based on input signal optical power and output optical signal power.

An optical fiber for amplification includes a core having an inner core and an outer core surrounding the outer circumferential surface of the inner core. The relative refractive index difference of the inner core to a cladding is smaller than the relative refractive index difference of the outer core to the cladding. The outer core is entirely doped with erbium. The theoretical cutoff wavelength of an LPmode light beam is a wavelength of 1,565 nm or more. The theoretical cutoff wavelength of an LPmode light beam is a wavelength of 1,530 nm or less. The theoretical cutoff wavelength of the LPmode light beam is a wavelength of 980 nm or less.

Optical fiber for amplification and optical fiber amplifier using the same

An amplification optical fiber operable to propagate light beams in a plurality of modes in a predetermined wavelength range through a core doped with a rare earth element, wherein Expression (1) is satisfied, where a cutoff wavelength of a propagated highest mode light beam is defined as &#x3bb;max, under conditions in which the cutoff wavelength of the highest mode light beam is defined as &#x3bb;c, a shortest wavelength of the wavelength range is defined as &#x3bb;min, and a cutoff wavelength of a second-highest mode light beam to the highest mode light beam is &#x3bb;min.&#x3bb;&#x3e;0.5 &#x3bb;min+0.5 &#x3bb;max&#x2003;&#x2003;(1).

Amplification optical fiber and optical fiber amplifier

A plurality of coresis disposed around the center axis of a first claddingin a state in which an inter-core distance &#x39b; of cores adjacent to each other is equal, a refractive index nof the coreis provided higher than a refractive index nof the first cladding, and the refractive index nof the first claddingis provided higher than a refractive index nof a second cladding. Moreover, 5.8&#x2266;&#x39b;/MFD(2&#x3bb;c/(&#x3bb;c+&#x3bb;op))&#x2266;8 is satisfied, where the inter-core distance is defined as &#x39b;, a mode field diameter of the core is defined as MFD, a cutoff wavelength is defined as &#x3bb;c, and a wavelength of communication light incident on the coreis defined as &#x3bb;op.

Amplifying optical fiber and optical amplifier

The first claddinghas a two-layer structure formed of a solid inner layerA passed through the center axis of the first claddingand an outer layerB enclosing the inner layerA and the plurality of coreswith no gap. A refractive index nof the coreis provided higher than refractive indexes nand nof the inner layerA and the outer layerB, the refractive indexes nA and nB of the inner layerA and the outer layerB are provided higher than a refractive index nof the second cladding, and the refractive index nof the inner layerA is provided lower than the refractive index nof the outer layerB.

The present invention relates to a white light source. This white light source comprises a plurality of amplified spontaneous emission light generating sections each comprising at least an active fiber. At least two of the amplified spontaneous emission light generating sections are connected together in series. The plurality of amplified spontaneous emission light generating sections generate amplified spontaneous emission lights having at least partially overlapping wavelength ranges. Furthermore, a white light source of the present invention includes amplified spontaneous emission light generating sections each comprising at least an active fiber. At least one of the amplified spontaneous emission light generating sections comprises a mirror. If the white light source includes a plurality of amplified spontaneous emission light generating sections, at least two of the plurality of amplified spontaneous emission light generating sections are connected together in series to generate amplified spontaneous emission lights having at least partially overlapping wavelength ranges.

White light source

A tellurite glass as a glass material of optical fiber and optical waveguide has a composition of 0<Bi O &lE;20 (mole %), 0&lE;Na O&lE;35 (mole %), 0&lE;ZnO&lE;35 (mole %), and 55&lE;TeO &lE;90 (mole %). The tellurite glass allows an optical amplifier and a laser device that have broadband and low-noise characteristics. In a splicing structure of non silica-based optical fiber (as a first fiber) and a silica-based optical fiber (as a second fiber), optical axes of the first and second optical fibers are held at different angles &thgr; and &thgr; (&thgr; &ne;&thgr; ) respectively from a vertical axis of a boundary surface between their spliced ends, and a relationship between the angles &thgr; and &thgr; satisfies Snell's law represented by an equation of sin &thgr; /sin &thgr; &equals;n /n (where n is a refractive index of the first optical fiber and n is a refractive index of the second optical fiber) at the time of splicing the first and second optical fibers.

Optical fiber splicing structure

Tellurite glass, optical amplifier, and light source

A tellurite glass as a glass material of optical fiber and optical waveguide has a composition of 0<Bi,O,&lE;20 (mole %), 0&lE;Na,O&lE;35 (mole %), 0&lE;ZnO&lE;35 (mole %), and 55&lE;TeO,&lE;90 (mole %). The tellurite glass allows an optical amplifier and a laser device that have broadband and low-noise characteristics. In a splicing structure of non silica-based optical fiber (as a first fiber) and a silica-based optical fiber (as a second fiber), optical axes of the first and second optical fibers are held at different angles &thgr;,and &thgr;,(&thgr;,&ne;&thgr;,) respectively from a vertical axis of a boundary surface between their spliced ends, and a relationship between the angles &thgr;,and &thgr;,satisfies Snell's law represented by an equation of sin &thgr;,/sin &thgr;,&equals;n,/n,(where n,is a refractive index of the first optical fiber and n,is a refractive index of the second optical fiber) at the time of splicing the first and second optical fibers.

An optical amplifier includes an erbium doped fiber of which at least one of a core part and a clad part is doped with erbium, excitation light sources or exciting the optical fiber, optical means for inputting excitation light from the excitation light source and signal light to the Er-doped fiber, and an optical isolator. The erbium doped fiber is a 1.58 &mgr;m band optical fiber having an equivalent fiber length as a product of a fiber length (m) and an erbium doping concentration (ppm by weight), which length provides a signal gain obtained at a wavelength of the excitation light source used for excitation of the erbium doped fiber of more than a predetermined practical reference value.

Growing community of inventors

Mito, Japan

Hirotaka Ono