Abstract: An optical receiving apparatus branches an optical signal, photo-electric-converts the branched signals, and compensates dispersion in each of the converted electrical signals. Electrical-dispersion compensators respectively compensate the dispersion in the electrical signals using a transversal filter having plural taps. A dispersion control unit controls the dispersion compensation amount for each of the electrical signals by adjusting tap coefficients of the transversal filter. A delay control unit controls the difference in the delay time of the electrical signals by adjusting the tap coefficients adjusted by the dispersion control unit. An identifying circuit identifies data in the optical signal based on each of the electrical signals that have been subjected to dispersion compensation by each of the electrical-dispersion compensators.

Abstract: An optical modulation device including waveform shapers that waveform-shape input data signals in synchronism with a rising or falling timing based on comparison with a reference level of an input clock signal, a multi-level phase modulator that generates a multi-level-phase-modulated optical signal based on the data signals waveform-shaped by the plurality of waveform shapers, and outputs the generated optical signal, and a level ratio controller that varies a relative level ratio of the reference level to an amplitude level of the clock signal input to the waveform shapers, based on the optical signal output from the multi-level phase modulator.

Abstract: An optical transmission system that alleviates waveform distortions due to nonlinear effects in fibers. A transmitter sends WDM signals to a receiver over a dispersion-managed optical transmission line with in-line optical repeaters. The transmission line is divided into a plurality of dispersion compensation intervals each composed of a main segment and a compensation segment. Chromatic dispersion is managed such that the dispersion compensation intervals have a non-zero net dispersion at every boundary point between them, or such that the number of zero-dispersion boundary points is reduced. The main segment is a series of repeater sections with negative dispersion, while the compensation segment is a single repeater section with positive dispersion.

Abstract: According to an aspect of an embodiment, an optical modulation device includes a Mach-Zehnder modulator and a controller. The Mach-Zehnder modulator is supplied a drive signal and a bias voltage. The Mach-Zehnder modulator modulates inputted light on the bases of the drive signal and the bias voltage. The drive signal selectively is superimposes a predetermined frequency signal. The bias voltage selectively is superimposes the predetermined frequency signal. The controller selects a superimposing target which is the drive signal or the bias voltage so as to change modulation formats.

Abstract: An optical transmission system that alleviates waveform distortions due to nonlinear effects in fibers. A transmitter sends WDM signals to a receiver over a dispersion-managed optical transmission line with in-line optical repeaters. The transmission line is divided into a plurality of dispersion compensation intervals each composed of a main segment and a compensation segment. Chromatic dispersion is managed such that the dispersion compensation intervals have a non-zero net dispersion at every boundary point between them, or such that the number of zero-dispersion boundary points is reduced. The main segment is a series of repeater sections with negative dispersion, while the compensation segment is a single repeater section with positive dispersion.

Abstract: The disclosed optical transmitter and control method include performing phase modulation of a light propagating through a corresponding optical path in accordance with a data signal, supplying bias voltages for regulating an operating point of each of phase modulation performed, imparting a predetermined phase difference, supplying bias voltages for phase difference regulation and coupling lights output from the corresponding optical paths. The optical transmitter includes superimposing a pilot signal on either one of bias voltages where the pilot signal has a frequency lower than a frequency of a bit rate of the data signal, and performing a feedback control in accordance with a result of monitoring.

Abstract: A plurality of pump light sources generate plural variations of pump light having different frequencies. A modulation circuit intensity-modulates the plural variations of pump light in the predetermined periods, respectively. A pump light pair whose frequency difference equals a Raman shift frequency are modulated such that they cannot simultaneously enters an emission state. A wavelength-multiplexer wavelength-multiplexes the plural variations of pump light modulated by the modulation circuit. A optical guide device guides the plural variations of pump light wavelength-multiplexed by the wavelength-multiplexer to an optical fiber.

Abstract: The present invention is a miniaturized differential M phase-shift modulator (M=2n: n is 2 or more) in which a plurality of Mach-Zehnder type light modulators each adapted to output a DPSK-modulated signal light by applying a driving voltage signal are arranged in parallel and that comprises a multiplexing waveguide adapted to output a DMPSK-modulated light by multiplexing outputs of the plurality of the Mach-Zehnder type light modulators, wherein a phase-shift voltage to produce a phase shift difference of substantially 2?/M for a plurality of the signal lights multiplexed by the multiplexing waveguide is applied to the plurality of the Mach-Zehnder type light modulators together with the driving voltage signal.

Abstract: A signal Data1 and Data2 are output from a DQPSK signal source. The output signal is input to the modulator drivers 1 and 2 of the differential output. A drive signal is applied from the drivers 1 and 2 to a modulator, and modulated light is output. An optical coupler 20 branches modulator output, and a power monitor 21 detects the power of the branched light. A detection result is transmitted to an amplitude control unit 22. The amplitude control unit 22 adjusts the amplitude of the drivers 1 and 2 such that the detection result of the power monitor 21 can be the maximum.

Abstract: An optical wiring switching unit includes a first connection interface. A packet switch includes a second connection interface. A resource includes a third connection interface, and is formed with at least one of a server and a storage device. A control device controls the optical wiring switching unit to perform a switching of connection between the connection interfaces. The packet switch and the resource are connected to the optical wiring switching unit via the connection interfaces. A network is configured by connecting the packet switch and the resource with a control of the optical wiring switching unit.

Abstract: It is an object of the present invention to provide a Raman amplifier capable of easily reducing the wavelength deviation of a Raman gain while suppressing system performance degradation, and an optical transmission system using such a Raman amplifier.

Abstract: An optical power information receiving unit receives optical power information transmitted from a power monitor. When it is judged that a new IT apparatus is connected to an optical switch, an optical switch control unit controls the optical switch to connect the IT apparatus and an optical switch control device. A control device port setting unit changes an IP address of an apparatus information acquiring port based on a control device setting address of an address information storing unit. An apparatus information acquiring unit acquires an IP address of the IT apparatus.

Abstract: Before wiring of a physical wiring changing-over switch is switched, a communication suspension instructing unit in a controller sends a signal to instruct IT devices connected to the physical wiring changing-over switch to suspend communications for a certain period of time and hold the communication bit strings to be transmitted in a temporary storage area. The signal is sent via an exclusive control line between the controller and the IT devices.

Abstract: A plurality of optical repeaters are provided on a transmission line between an optical transmitting station and an optical receiving station. A combined transmission line section is provided between optical repeaters. The combined transmission line section is composed of the first optical fiber, which is a positive-dispersion fiber, and the second optical fiber, which is a negative-dispersion fiber. Signal light is inputted to the first optical fiber in each combined transmission line section. Each optical repeater inputs pump light to the second optical fiber.

Abstract: In a network, a controller controls a physical-interconnection selection switch and middle switches so as to dynamically change a network topology according to the state of the network. A traffic analyzer detects how the traffic in the network changes. If there is a change in traffic, the controller controls the physical-interconnection selection switch and the middle switches so as to change the network topology to one suitable for the changed traffic.

Abstract: An optical communications system and transmission section repair method is provided to prevent the dispersion value in an optical receive station from being affected when a transmission line has been obstructed, wherein a patch is made into the transmission line adjusted for dispersion in the relay section of the transmission line. The transmission line includes positive dispersion fiber and negative dispersion fiber. The optical fiber used to patch the transmission line is an optical fiber where the absolute value of the dispersion is smaller than the dispersion value of the positive dispersion fiber or the negative dispersion fiber.

Abstract: The present invention provides an information processing system which comprises multiple processor nodes creating parallel computers, an information transmission line for connecting the processor nodes, and a separation switch provided on the information transmission line for separating the information transmission line so that the processor nodes create multiple parallel computers independent of one another.

Abstract: The present invention provides an information processing system, comprising a plurality of calculation nodes with an optical transmitter, which individually outputs a plurality of optical signals each having a different wavelength, and an optical receiver, which individually receives a plurality of optical signals each having a different wavelength, an optical transmission path connecting a plurality of the calculation nodes to each other, and optical pathway switching unit, lying in the optical transmission path, for transmitting the optical signal to the specific calculation node in accordance with a wavelength of the optical signal output from one of the calculation nodes.

Abstract: An optical transmission line including first, second and third fibers so that an optical signal travels through the first, second and third fibers, in order. The first fiber has a positive dispersion for a wavelength of the optical signal. The second fiber has a negative dispersion for the wavelength of the optical signal and a mode field diameter smaller than a mode field diameter of the first fiber. The third fiber has a mode field diameter smaller than the mode field diameter of the second fiber. Pump light is provided to the third fiber so that Raman amplification occurs in the transmission line.

Abstract: An optical transmission system that can reduce a difference of Raman gain between each of upstream and downstream lines, in a system configuration in which Raman amplification is performed for both the upstream and downstream lines by a common Raman amplifier. Transmission sections are provided for both the upstream and downstream lines, and when pumping light, generated by a common pumping light source, is supplied to the transmission sections of the one line and the transmission sections of the other line, the negative dispersion fibers having different wavelength dispersion values are applied to the positive and negative hybrid transmission paths used for the transmission sections of each line, so that the length of each negative dispersion fiber is made substantially equal to each other.