Abstract: The present invention provides a method and device for routing and wavelength assignment in an optical network. The method comprises: a topology step in which a topology network of the optical network is obtained; a route calculation step in which at least one route in the topology network is calculated, a first node and a last node of the route being predetermined, and the at least one route being part of all routes from the first node to the last node; and a wavelength assignment determination step in which for each node on the route, it is determined whether link attribute information of the node meets a predetermined constraint condition, if the predetermined constraint condition is met, the route is selected as a working route, and the method ends; if the predetermined constraint condition is not met, the method returns to the route calculation step.

Abstract: Disclosed are universal QPSK transmitter structures and methods for generating different QPSK signals exhibiting different polarization schemes, namely PolMux, PolMod and PolSw. The bit rate of the generated signals is variable, thereby allowing the transmitter to adjust to varying network traffic conditions. Advantageously, the generated signals may be detected by analog receivers (PolSw-QPSK) and coherent receivers (PolMux-QPSK, PolMod-QPSK, and PolSw-QPSK).

Abstract: The invention relates to a system for producing a signal having a variably adjustable time position or phase position, comprising at least one light source for producing a first light component (2) having a first wavelength and a second light component (2?) having a second wavelength deviating from the first wavelength and a phase modulator (5) for varying a phase of the first light component (2), wherein the system is designed to produce a beat note signal by superposing the two light components (2, 2?) and has a common optical fiber (4) for coupling in both light components (2, 2?), wherein furthermore the phase modulator (5) is arranged at an end or in the course of said optical fiber (4) and is transparent to both light components (2, 2?) and is designed to vary the phase of the first light component (2) selectively independently of a phase of the second light component (2?) or more intensely than the phase of the second light component (2?). The invention further relates to a use of such a system.

Abstract: This disclosure describes the Fast Chromatic Dispersion Estimation (FCDE) techniques which corrects for chromatic dispersion in high data rate optical communications systems such as some coherent optical communications systems. FCDE may utilize transform such as fast-Fourier transforms to estimate the chromatic dispersion. From an estimation of the chromatic dispersion, the techniques may determine filter tap coefficients for compensating the chromatic dispersion.

Abstract: Methods and systems of data symbol recovery in a coherent optical receiver of an optical communications system. A respective probabilistic phase error is calculated for each of a plurality of data symbol estimates. A phase rotation is calculated based on the probabilistic phase error estimates, using a filter function, and the phase rotation applied to at least one data symbol estimate to generate a corresponding rotated symbol estimate. Each rotated symbol estimate is processed to generate corresponding decision values of each data symbol.

Abstract: A method is provided for carrying out dispersion compensation in an optical mesh network supporting simultaneously traffic services being provided at two or three different bit rates including a basic bit rate being 10 Gbps and at least one higher bit rate selected from among 40 Gbps and 100 Gbps. The method comprises the following steps: providing in-line dispersion compensation for every span in the network so as to reach positive average residual dispersion RDS per span extending to less than about 3 km; providing start points of possible trails in the network with respective external, pre-compensation negative Dispersion Compensation modules (DCMs), and providing termination points of possible trails in the network with respective external post-compensation positive DCMs.

Abstract: There is provided an optical receiver. The optical receiver includes a board to be coupled with an optical transmission line array, an optical diode array disposed on the board, and the optical diode array including a plurality of photo diodes each of which receives light from a corresponding optical transmission line in the optical transmission array. Further bias suppliers, conversion circuits, and capacitors are provided on the board or a real side of the board. Each of the photo diodes includes a first electrode and second electrodes, the first electrode receives a bias voltage supplied by a bias supplier, a current signal flowing through the second electrode is converted by a conversion circuit into a voltage signal, and one end of a capacitor is coupled to the first electrode and the other is grounded.

Abstract: A detection system for remote monitoring of a contact condition comprises first, second, and third impedance means, and four comparators. Each impedance means is selectively coupled between the contact and the comparators. With a known voltage applied at the third impedance means, the three impedances produce a unique signal voltage at the comparators depending on a condition of the contact closure. Each comparator may detect one of the four unique voltages and produce an electrical signal corresponding to the detected condition, which may be converted into an optical signal, and be transmitted in a fiber optic cable to a receiver where it is converted back into an electrical signal. Four detectors are each adapted to detect one of the electrical signals, and trigger a relay and status LEDs, indicating a contact condition consisting of: normally open/closed, and short/open circuited. A fifth detector monitors for broken fiber optic cable.

Abstract: A device able to evaluate a phase difference between I-component and Q-component of signal light generated by an optical hybrid is disclosed. The device includes a detector, a compensator and an evaluator. The detector detects positive and negative elements of each of the I-component and the Q-component. The compensator generates a compensated I-component and a compensated Q-component so as to keep the sum of positive and negative elements of each of components in constant. The evaluator determines the phase difference via an ellipsoid drawn by the compensated I- and Q-components.

Abstract: An optical access network comprises L wavelength division multiplexed access sub-networks. Each of the wavelength division multiplexed access sub-networks is arranged to use a set of wavelength channels. M optical line termination apparatus, each receive traffic from a respective operator network and output traffic on the wavelength channels. A wavelength routing apparatus comprises M sets of first ports and L second ports. Each set of first ports connects to a respective one of the optical line termination apparatus and each second port connects to an optical link of a respective one of the wavelength division multiplexed access sub-networks. The wavelength routing apparatus is arranged to route the set of wavelength channels between the sets of first ports and the second ports and to route different wavelength channels of the same wavelength to different ones of the second ports.

Abstract: The present invention is to provide a method applicable to a fiber-optic transceiver including a transmitter optical subassembly (TOSA) provided therein with a laser diode, but without a monitoring photodiode, a laser driver controlled by a controller IC for driving the laser diode to generate a laser beam, and a thermal sensor for sensing temperature of the laser diode. The method includes executing an approximation process to characteristic data, i.e.

Abstract: A technique for monitoring at least a network portion of an optical communication network, by monitoring changes of a decision threshold used for discriminating a digital optical signal being propagated via the network portion.

Abstract: A data transmission apparatus for use in a separate-type base station is provided. The data transmission apparatus includes: a digital unit configured to generate first data that includes transmission method information indicating a selected transmission method and data to be transmitted; a time-division synchronization control unit configured to, in response to the selected transmission method being time-division multiplexing (TDM), generate second data by including synchronization information for transmitting the first data using TDM in the first data; and a wavelength conversion unit configured to convert at least one of the first data and the second data into one or more wavelength optical signals using a predefined wavelength or a predefined group of wavelengths and transmit the wavelength optical signals to one or more radio stations.

Abstract: An embodiment of the invention is an optical node configured to transmit/receive a wavelength-division-multiplexed signal. An optical monitoring unit monitors power levels of the wavelength-division-multiplexed signal on a wavelength-by-wavelength basis to acquire wavelength-by-wavelength power level values of the optical signals. A comparison arithmetic unit performs a comparison between each of the acquired wavelength-by-wavelength power level values of the optical signals, and a predetermined upper limit value and a predetermined lower limit value. A target value calculation unit determines target values of power levels at wavelengths whose acquired power level values exceed the upper limit value to be values between a center value and the upper limit value, and determines target values of power levels at wavelengths whose acquired power level values fall below the lower limit value to be values between the center value and the lower limit value.

Abstract: The present invention has an object to provide an optical modulation device and an optical modulation method that achieve an excellent spectral efficiency with a simple and compact configuration and low power consumption. An optical modulation device according to an exemplary aspect of the present invention includes a CW light source (11), a coupler (12), optical modulators (14a) and (14b), an optical frequency shifter (15b), a serial-to-parallel converter (21), and a delay circuit (24a). The serial-to-parallel converter (21) divides a data signal having a bit rate B into two data strings having a bit rate B/2, and extracts a clock signal (CLK). The delay circuit (24a) temporally synchronizes the two data strings. CW light emitted from the CW light source is split into two beams by the coupler (12). The optical modulators (14a) and (14b) generate optical signals by modulating the two split light beams according to the data strings.

Abstract: A signal transmission and reception device and method are provided. The transmission method comprises generating multiple optical carriers from a basic optical carrier; modulating optical carriers, except for a predetermined optical carrier, in the optical carriers by using multiple data signals respectively, to generate multiple optical modulated signals; and synthesizing the multiple optical modulated signals and the predetermined optical carrier into a single optical signal, and transmitting the signal.

Abstract: For determining OSNRreal of a real optical signal carried in an optical network link, the following has been proposed: tapping a portion of the real optical signal, altering the tapped signal portion by adding to it in-band artificial noise signal, thus obtaining a combined signal, scattering the combined signal by stimulated Brillouin or Raman scattering (SBS or SRS) in an optical element, extracting a signal back reflected by SBS/SRS from the optical element, determining OSNRcomb of the back reflected signal and deriving the OSNRreal from the OSNRcomb knowing absolute and/or relative power of the added artificial noise.