Kddi Corporation

Other

Kokusai Denshin Denwa Kabushiki Kaisha

Kdd Corporation

Tomohiro Otani

Masatoshi Suzuki

Takehiro Tsuritani

Shu Yamamoto

Koji Goto

Tetsuya Miyazaki

Michiaki Hayashi

Toshio Kawazawa

Noboru Edagawa

Hiroharu Wakabayashi

Yasuyuki Nagao

Noboru Yoshikane

Haruo Abe

Jun Haeng Lee

Masando Tanaka

The present invention relates to the quality monitoring of optical signals, which have different symbol rates and generated by different modulation schemes, used for example in a wavelength division multiplexing network. The apparatus according to the invention includes an optical splitter for outputting the input optical signal to a first optical route and a second optical route, an optical coupler for coupling a optical signal from the first optical route with a optical signal from the second optical route, a delay unit provided on the first optical route, and a phase shift unit provided on the first optical route or the second optical route.

Optical signal quality monitoring apparatus

A link connectivity verification message to recognize a physical link connection state is transmitted from the WDM to the PXC on a C-plane. The PXC transmits a link connectivity verification ACK message including information representing a physical link connection state, and the WDM transmits a cross-connect instruction message to cross-connect a transmission side and a reception side of a port (port) of the PXC. Probe light transmitted from the port (port a) of the WDM is turned back by a cross-connect of the port (port) of the PXC. The WDM receives the probe light to verify a link connectivity.

Link connectivity verification method

An optical signal is transmitted via a transponder, an all-optical node, and a WDM deviceincluding an optical filter. A control means which includes a route and wavelength selecting functional part, transmits a request band information and a wavelength information based on a requested band information, link information of a network, and band limitation information with respect to each filter wavelength of the optical filter. A multi-rate functional partsends a bit rate varying request to set a band to be requested to the network side according to the requested band information. A wavelength varying functional partsends a wavelength varying request to set a wavelength of the optical signal according to the wavelength information. The optical filterincludes a bit rate (band) dependent wavelength multiplexing and demultiplexing functional part

Wavelength service providing apparatus in all-optical network

Between photonic cross connects (PXCs)andan in-use system path passing through transmission apparatus (WDMs)andare set, and a backup system passing through transmission apparatus (WDMs)andis set. The WDMsandlink to the PXCsandand release masking therebetween when the in-use system path is set, and set masking therebetween when the in-use system path is deleted. The WDMsandincluded in the in-use system path transmit an alarm to a monitoring system when an input light is turned off, and the WDMsandincluded in the backup system path do not transmit an unintended alarm to the monitoring system even when the input light is turned off.

Link system for photonic cross connect and transmission apparatus

To realize a highly reliable monitor control signal network at low costs, a data transmission system comprises a first network to optically transmit a data signal and a monitor control signal, first and second nodes connecting to the first network, and a second network capable of transmitting the monitor control signal. The first node comprises a demultiplexer to demultiplex the data signal and the monitor control signal out of the signal light from the first network, a signal distributor having a plurality of input ports and a plurality of output ports to distribute the data signal demultiplexed by the demultiplexer into designated output port, a controller to control the signal distributor and to monitor each part in the first node, a first selector to select one of the monitor control signal demultiplexed by the demultiplexer and the other monitor control signal entered from the second network and to apply the selected one to the controller, a second selector to output the monitor control signal output for the second node output from the controller toward one of the first network and the second networks, and a multiplexer to multiplex the monitor control signal output for the first network output from the second selector and the data signal output from the signal distributor and to output the multiplexed signals onto the first network.

Data transmission system, transmission method of optical network monitor control signal, and node

The present invention regenerates optical signals in an intact optical state according to a low-speed optical clock. In one embodiment, an optical splitter applies a portion of optical pulse signals to a clock recovery circuit and the rest to an optical splitter. The optical splitter applies half of the input signal to an optical regenerator and the rest to another optical regenerator. The clock recovery circuit regenerates an electric clock signal with half the frequency of the input optical pulse and applies the clock to an optical clock pulse generator. The optical clock pulse generator generates an optical clock signal with half the frequency of the input optical pulse whose phase matches with that of the optical signal at the optical regenerator. An optical regenerator regenerates the optical signal from the optical splitter in an intact optical state. A polarization combiner combine the optical signals from the optical regenerators in mutually orthogonal polarization.

Optical signal regenerator

An optical reception apparatus comprises an optical receiver to receive an optical signal from an optical transmission line, an error corrector to correct an error of the received signal and to transmit the error-corrected signal and error rate information before error correction, a judging apparatus to judge transmission quality of the optical transmission line according to the error rate information from the error corrector and a threshold value equal to an error rate lower than an error correction limit of the error corrector, and a selective breaker to transmit the signal whose error is corrected by the error corrector in normal state and to block transmission of the signal whose error is corrected by the error corrector when the judged result by the judging apparatus indicates deterioration of the transmission quality of the optical transmission line.

Optical reception apparatus and optical transmission system

An optical clock multiplier comprises a phase modulator ( ) to shift a phase in pulse duration of an input optical clock pulse by &pgr;, a polarization mode dispersion device ( ) having a predetermined time difference between first and second polarizations orthogonal to each other to divide an output light from the phase modulator into the first and second polarization components, and a polarization device ( ) to extract one of polarization components in a third polarization practically inclined at an angle of 45&deg; against the first polarization and a fourth polarization orthogonal to the third polarization out of the output light from the polarization mode dispersion device.

Optical clock multiplier and method thereof

A four fiber ring network optical switching circuit capable of realizing the bridge function at times of the span switching and the ring switching economically by a very compact structure is disclosed. A four fiber ring network optical switching circuit is formed by a 10&times;8 optical matrix switch having ten input ports and eight output ports, and two branching elements adapted to branch each one of two optical signals among eight optical signals that are inputs of the four fiber ring network optical switching circuit, into two identical optical signals, and to enter the two identical optical signals into two input ports of the 10&times;8 optical matrix switch such that the eight optical signals are entered into the ten input ports of the 10&times;8 optical matrix switch as ten optical signals.

Four fiber ring network optical switching circuit using branched inputs

In a signal demultiplexing device formed by a probe light source, a wavelength converter, and a wavelength demultiplexer, the probe light source is formed by a plurality of sub-probe light sources configured to respectively generate the sub-probe lights with the prescribed different wavelengths for respective time-slots, a multiplexer configured to multiplex the sub-probe lights generated by the plurality of sub-probe light sources, and a phase different giving unit configured to give phase differences corresponding to time-slot positions to the sub-probe lights multiplexed by the multiplexer, and to sequentially output the sub-probe lights with the phase differences in correspondence to respective time-slots.

Signal demultiplexing device and signal routing device in high speed transmission system

An optical digital regenerator for digitally regenerating an input signal in an intact optical state. A first operating unit has a first probe light generator for generating a first probe light and a first optical operator for converting a waveform of the first probe light output from a first probe light generator according to an optical intensity waveform of the input signal light. A clock extractor extracts a clock component of the input signal light from a photocurrent generated by the first optical operator. A second optical operating unit has a second probe light generator for generating a second probe light pulsed in accordance with the clock output from the clock extractor and a second optical operator for sampling the second probe pulse light output from the second probe light generator.

Optical digital regenerator

In an optical transmission system, an optical transmission line has up and down systems and loops back a supervisory light between the up and down systems. Trunk stations are provided at both ends of the optical transmission line and one or more optically branching units are provided in the optical transmission line for add/dropping a specific wavelength respectively. A branch station is connected to each of one or more the branching units. A bypass line for bypassing the supervisory light is provided in each of the one or more optically branching units.

Optical transmission system, optically branching apparatus and optical signal processing apparatus

A demultiplexer device is used in a wavelength-division multiplexed optical fiber communication line to achieve efficient dispersion compensation and loss compensation as well as a reduction of active devices such as optical amplifiers. The demultiplexer device has a series of couplers disposed in multi-stages from the input of the demultiplexer. Each coupler has two branches with one branch of each coupler connected to a separate optical filter and the other branches are series connected to a subsequent stage of the couplers through equalizing fibers, except for the final stage which has its second branch connected to an optical filter for the shortest wavelength transmitted. The equalizing fibers are thus serially connected between couplers and act to perform a cumulative dispersion compensation. The quantity of the equalizing fibers can thus be reduced as a whole, and as a result the attenuation amount also decreases, so that the number of optical amplifiers can be reduced.

Demultiplexer device for wavelength-division multiplexed optical fiber

A method of suppressing noise and improving the optical transmission characteristic of a wavelength division multiplexing transmission system provides lights for suppressing noise from the light sources (NS1 and NS2) which are multiplexed on the wavelength division multiplexed signal. Consequently, the S/N ratio of each channel of a wavelength division multiplexed signal which propagates through the optical path can be improved.

Growing community of inventors

Saitama, Japan

Tomohiro Otani