Nippon Telegraph and Telephone Corporation

Showa Denko K.k.

Kohei Saito

Hiroki Kawahara

Takeshi Seki

Sachio Suda

Tsutomu Kubo

Takashi Kotanigawa

Kenta Hirose

Fukutaro Hamaoka

Toshiya Matsuda

Akira Naka

Minoru Yamaguchi

Kenji Miura

Yoichiro Sakaguchi

Kunihiro Kuroki

A wavelength cross-connect device is formed by connecting a plurality of wavelength cross-connect devices in a ring-like form with WDM networks for each band of a plurality of bands on the input/output sides of the wavelength cross-connect devices, and includes a link wavelength allocation control unit. The link wavelength allocation control unit performs control to set different optical paths through which optical signals of the same wavelength are transmitted in the same zone between wavelength cross-connect devices, in the WDM networks of different bands in the same zone.

Wavelength cross connect device, multiband transmission system, and multiband transmission method

A wavelength cross-connect device performs a relay process in which multiple wavelength signal light beams that have been transmitted in multiple bands from a plurality of paths and demultiplexed into optical signals in the respective wavelength bands for each path are amplified, are switched to paths by contention WSSs, and are output to paths on the output side. A WXC unit performs the relay process on an optical signal in a specific wavelength band. An input-side conversion unit that converts a wavelength band other than the specific wavelength band into the specific wavelength band is provided on the input side, and an output-side conversion unit that converts the specific wavelength band after the conversion into the wavelength band prior to the conversion is provided on the output side. A directly-input optical signal in the specific wavelength band is directly output after the relay process at the WXC unit.

Wavelength cross connect device and wavelength cross connect method

An optical node device includes a transmission transponder, WSSs, a beam splitter, and a monitoring transponder. The transmission transponder transmits an optical signal via an optical path set in an optical fiber. The WSSs ultiplex, on the transmitted optical signal, a monitoring control signal for performing optical path tracing that is confirmation of conduction along the optical path. The monitoring transponder measures and monitors the optical power of the monitoring control signal multiplexed into the optical signal branched by the beam splitter, and further monitors whether the monitored optical power is equal to or higher than a predetermined level indicating normality of the optical path.

Optical node device, optical transport network system, optical path trace method and program

A wavelength cross-connect device performs relay processing, the relay processing being such that wavelength multiplexed signal lights, which are multiband transmitted from a plurality of routes, are demultiplexed into different wavelength bands, and for each route, respective optical signals of the different wavelength bands are amplified, then subject to route change by WSSs and outputted to output side routes M. The device includes C-band WXC units that are the same in total number as the wavelength bands of the optical signals of the respective wavelength bands and perform relay processing on optical signals of a specific wavelength band of the different wavelength bands.

[Problem] To reduce a filter penalty caused by narrowing of an optical signal band due to optical filters having a multiplexing/demultiplexing function in an optical transmission line between transponder units. [Solution] In an optical transmission systemA, transponder unitstoandtoconnected by optical fibersin which optical filters having a multiplexing/demultiplexing function of an optical signal are interposed include a transmission unitthat transmits the optical signal obtained by modulating laser light from a laser light sourcewith an electric signal from a communication apparatus to the optical fibers, and a reception unitthat receives the optical signal from the optical fibersand converts the received optical signal into an electric signal. The reception unitincludes a BER measurement unit that measures a BER, based on a received signal, and feeds the measured BER back to a transmitting side. The transmission unitincludes a frequency shift control unit that performs frequency shift control of making a center frequency of the laser light match a center frequency of the received optical signal so that the fed back BER is minimized.

Optical transmission system and filter penalty reduction method

A cyclic wavelength band permutation device () includes as many wavelength band converters (to) as the wavelength bands of optical signals (S, C, and L), and the wavelength band converters are individually connected to the output terminals of corresponding optical amplifiers among a plurality of optical amplifiers (to) connected to an optical fiber () in an inserted manner. When a wavelength-multiplexed signal beam obtained by multiplexing optical signals in different wavelength bands is multiband-transmitted through an optical fiber while being amplified by the plurality of optical amplifiers, each wavelength band converter performs a cyclic permutation process of transitioning or converting an optical signal allocated to the shorter wavelength band side in the bands of the optical fiber to the longer wavelength band side, and also transitioning or converting an optical signal allocated to the longest wavelength band to the shortest wavelength band.

Cyclic wavelength band replacement device, multi-band transmission system, and cyclic wavelength band replacement method

An OSNR spectrum estimation apparatus includes an OSNR estimation unit configured to cause an optical node to estimate an OSNR of a predetermined transmission line using a probe light of a predetermined wavelength in a predetermined number of wavelength channels, the predetermined number being less than the number of all wavelength channels; and an OSNR spectrum calculation unit configured to calculate an OSNR spectrum of all the wavelength channels from OSNRs of the predetermined number of wavelength channels measured by the optical node.

OSNR spectrum estimation apparatus, OSNR spectrum estimation method, and program

A fault location in an optical cable at a long distance is easily measured and detected with low-cost equipment in a configuration in which an isolator is disposed in the vicinity of an optical amplifier for improved optical transmission performance and for stabilization. An optical amplifier has a configuration in which multiplexing/demultiplexing units as first WDM filters and that multiplex/demultiplex main signal light and OTDR light and (measurement light) for submarine cable fault measurement transmitted to a submarine cable in opposite directions from a transmission device side and a reception device side, transmit the multiplexed/demultiplexed main signal light to a main path passing through an isolators and an EDF, and transmit the multiplexed/demultiplexed OTDR light to a bypass path bypassing the isolators and the EDF are included on both sides of a set of the isolators and the EDF of the submarine cable.

Optical amplifier, optical transmission system, and optical cable failure part measurement method

[Problem] A signal distortion generated when a multi-level modulated optical signal is transmitted through an optical transmission path where optical amplifiers are scattered is suppressed and transmission quality is improved. [Solution] An optical transmission systemincludes Txto Txconfigured to transmit a multi-level modulated optical signalto an optical fiber, optical amplifierstoconfigured to amplify the optical signaltransmitted through the optical fiber, the optical amplifierstobeing scattered on the optical fiber, and Rxto Rxconfigured to receive the amplified optical signalvia the optical fiber. A pre-dispersion compensation unitof each of the Txto Txperforms pre-dispersion compensation on the transmitted optical signal, based on a pre-dispersion compensation ratio for determining a percentage of dispersion compensation to be performed in advance on a wavelength dispersion to be accumulated in the optical fiber, with respect to the dispersion compensation to narrow a bandwidth to be widened by the wavelength dispersion during transmission of the optical signalthrough the optical fiber

Dispersion compensation designing device, dispension compensation method, optical transmission system, and program

A radical-polymerizable resin composition comprising one or more metal-containing compounds (A) selected from a metal soap (A1) and a &#x3b2;-diketone skeleton-containing metal complex (A2); one or more thiol compounds (B) selected from a secondary thiol compound (B1) and a tertiary thiol compound (B2); and a radical-polymerizable compound (C) can stably cure under a dry condition, in water and in seawater and further on a wet substrate. The radical-polymerizable resin composition is useful as a repairing material for inorganic structure, a radical-polymerizable coating composition, a concrete spall preventing curable material, a reinforcing fiber-containing composite material, etc.

Radical-polymerizable resin composition, curing method thereof, method of producing same, use of radical-polymerizable resin composition, and use method of thereof

A receiver is configured to have two coherent receivers using two pieces of local oscillator of optical frequencies fand fclose to optical frequency fof signal light, the two pieces of local oscillator being controlled to have a predetermined optical frequency spacing &#x394;F, and a digital signal processor demodulating transmission data signal sequences based on outputs from the coherent receivers. When the frequency difference &#x394;fof one of the two pieces of local oscillator from a virtual reference frequency f' close to the optical frequency fof the signal light is set, the digital signal processor obtains the frequency difference &#x394;fof the other of the two pieces of local oscillator by calculating &#x394;f&#x2212;&#x394;F, inputs electric signals output from the two coherent receivers, and compensates the phase rotation caused in the electric signals by frequency differences &#x394;fand &#x394;f

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Tokyo, Japan

Kohei Saito