Abstract: In optical networks new links are added between nodes over time to satisfy the increasing traffic demands of the network. Existing links are normally not changed, resulting in a network that does not have the lowest energy consumption. A method provides a way to reduce the energy consumption of the overall network while supporting the required traffic demands at all times. The network includes a multiple source nodes, and multiple destination nodes. The network is represented by a graph of nodes connected by edges, wherein each node represents an optical network element and each edge represents a path connecting two optical network elements. Each edge is labeled with a demand. The non-bridge edge with a lowest demand is removed from the graph, and the lowest demand is added to the non-bridge edge with a highest demand. These steps are repeated until a termination condition is reached.

Abstract: An optical packet switching device is provided with: a first input unit and a second input unit for receiving optical packet signals having destination information and information of a wavelength in use; an optical switch unit for routing the optical packet signals; a branching unit for branching the received optical packet signals; an analyzer unit for analyzing the header of the branched optical packet signals so as to detect the destination information and the information of the wavelength in use; and an output competition determination unit for checking for temporal competition of the optical packet signals based on the destination information and for determining whether the optical packet signals should be transmitted or discarded based on the information of the wavelength in use when there is competition.

Abstract: Carrier phase estimation techniques are provided for processing a received optical signal having a carrier modulated according to a modulation scheme. First and second carrier phase estimation operations are performed on a digital signal derived from an optical carrier obtained from the received optical signal using coherent optical reception. The first carrier phase estimation operation tracks relatively fast phase variations of the optical carrier of the received optical signal to produce a first carrier phase estimation and the second carrier phase estimation operation tracks relatively slow phase variations of the optical carrier of the received optical signal to produce a second carrier phase estimation. A difference between the first and second carrier phase estimations is computed. Occurrence of a cycle slip is determined when the difference is greater than a threshold. A correction is applied to the first carrier phase estimation when the low pass filtered difference exceeds the threshold.

Abstract: Various embodiments of the present invention relate to weighted waveforms for improved jam code effectiveness. In various examples, weighted waveforms for improved jam code effectiveness may be implemented in the context of systems, methods, computer program products and/or algorithms.

Abstract: An optical packet transmitter device includes: a detection unit for detecting packet-length information and priority information from a received Ether signal; a setting unit for setting, according to the degree of priority, a division factor by which the Ether signal is divided and a wavelength used for an optical packet signal to be transmitted; a header generation unit for generating a header containing destination information, the packet-length information, the priority information, and information of wavelength in use of the Ether signal; a transmission processing unit for dividing the Ether signal according to the set division factor and generating a plurality of packet signals; a header insertion unit for inserting the generated header in at least one packet signal; and an electrical/optical converter unit for converting the plurality of packet signals into optical packet signals of a plurality of wavelengths according to the set wavelength in use.

Abstract: A transponder for performing bidirectional conversion between a client-side signal used for communication to a client device and a transmission path-side signal used for communication to a transmission path, the transponder comprising: a client-side interface for inputting/outputting the client-side signal; a transmission path-side interface for inputting/outputting the transmission path-side signal; a connection determining unit for determining which of the another client-side interface and the client device is coupled to the client-side interface; and a transmission signal generating unit for outputting, in a case where a state signal indicating a state on a transmission path side is input to the transmission path-side interface, a transmission signal indicating that the state signal has been input, from the client-side interface, wherein: the transmission signal generating unit changes a form of the transmission signal to be output from the client-side interface, based on a determination result obtained by

Abstract: An optical packet switching device is provided with: a first input unit and a second input unit for receiving an optical packet signal having destination information and priority information; a first demultiplexer and a second demultiplexer for branching the optical packet signal; an optical switch unit for routing one of branched optical packet signals; a first analyzer unit and a second analyzer unit for analyzing the header of the other branched optical packet signal so as to detect the destination information and the priority information; and an output competition determination unit for checking for temporal competition of a plurality of optical packet signals based on destination information and for determining whether the optical packet signals should be transmitted or discarded based on priority information when there is competition.

Abstract: An adaptive signal processing method to achieve an increase in capacity of data transfer systems, in which control data is returned via a backward channel. The method provides signal processing using an electrical sub-carrier sub-division according to frequency, the electrical sub-carrier with the lowest carrier frequency being permanently used as the backward channel (RC) for transferring control information relating to the current transfer quality of each sub-carrier. An electrical modulation on N parallel sub-carriers takes place in the transmitter (Tx) and then an optical intensity modulation is carried out for a serial data transfer in the optical channel (IRWC). The discrete division of the information to be transferred to the sub-carriers in a real-time operation can take place by the implementation of specific bit-loading algorithms.

Abstract: A tunable optical demultiplexer includes a control circuit and one or more heaters thermally coupled to waveguides of an optical demux. The control circuit is in signal communication with the one or more heaters and includes a processor coupled to a memory. The control circuit is configured to receive an optical channel group (OCG) identification signal and adjust the power delivered to the heaters in response to the OCG identification signal and based on parameter values stored in the memory. The optical demux outputs a plurality of optical signals at a corresponding one of a plurality of outputs. The transmission characteristics of the optical demux are varied depending on the amount of power delivered to the heaters. The varying of the transmission characteristics of the optical demux adjusts the spectral shifting of the plurality of wavelengths output by the optical demux.

Abstract: A light transmitter receives a low-rate data signal having a low data rate and a high-rate data signal having a high data rate that is greater than the low data rate. The transmitter includes a light source and a light modulator to modulate the light source based on logic levels of the high-rate data signal and logic levels of the low-rate data signal, to produce modulated light that concurrently conveys the logic levels of the low-rate data signal and the logic levels of the high-rate data signal.

Abstract: Provided is a passive optical network system, wherein the electric power to be consumed is reduced on the basis of the quantity of signal to be transmitted downstream in a WDM-PON where signals having different transmission rates for wavelengths are mixed. In the passive optical network system, an OLT (200) and a plurality of ONUes (300) are connected by an optical fiber network including an optical splitter (100) and a plurality of optical fibers (110 and 120). The OLT (200) indicates to the ONUes (300) the wavelength to be used, in addition to the timing for transmission to the ONUes (300). A format for signal transmission from the OLT (200) to the ONUes (300) comprises both the region, in which the timing for transmission to the ONUes (300) indicated by the OLT (200) to the ONUes (300) is stored, and the region, by which the wavelength to be used in the communication in the direction from the OLT (200) to the ONUes (300) is indicated.

Abstract: A method and an apparatus are for directing an optical receiver toward a light source, using a plurality of light detectors arranged around the receiver's optical axis to check where light (L) hits the light detectors relative to the optical axis. The method includes the steps of: A) arranging the receiver defocused to embrace a largest possible field of view of the area wherein the light source may be located, and refracting the light with largest possible spread angle; B) letting the receiver search for the light source until the light (L) hits at least one of the light detectors; C) calculating where the light hits relative to the optical axis, and adjusting the receiver, directing the light toward the optical axis; D) reducing the field of view embraced by the receiver; and E) repeating the steps C and D until the light is concentrated in a smallest possible area.

Abstract: A system and method for polarization de-multiplexing in a coherent optical receiver. De-multiplexing is achieved using a modified constant modulus algorithm (CMA) wherein filter coefficients are determined as a function of a coupling coefficient to avoid convergence of the CMA outputs.

Abstract: In one embodiment, the opto-electronic assembly is a hybrid integrated circuit having an array of avalanche photodiodes (APDs) that are electrically coupled to a corresponding array of transimpedance amplifiers (TIAs), with both the APDs and TIAs being mounted on a common ceramic substrate. The opto-electronic assembly further has an optical subassembly comprising an arrayed waveguide grating (AWG) and an array of turning mirrors, both attached to a temperature-control unit in a side-by-side arrangement and flip-chip mounted on the substrate over the APDs. The opto-electronic assembly employs a silicon-based submount inserted between the APDs and the substrate to accommodate the height difference between the APDs and the TIAs. The submount advantageously enables the placement of APDs in relatively close proximity to the turning mirrors while providing good control of the APD's tilt and offset distance with respect to the substrate.

Abstract: A method for optical layer traffic grooming includes receiving at least two optical input signals into respective optical receivers, each optical receiver having a photodetector for converting the respective optical input signal into a respective electrical signal; a grooming processor responsive to the electrical signals, the grooming processor being a radio frequency RF processor for processing the electrical signals at a subcarrier level to produce an RF orthogonal frequency division multiplexing signal OFDM signal; and modulating the groomed RF OFDM signal at a transmitter for conversion of the groomed RF OFDM into an optical signal.

Abstract: A dynamic bandwidth allocation apparatus 12 of the present invention is mounted on, for example, an optical line terminal 1 in a PON system that relays upstream frames F1 and F2 received from optical network units 2, to upper networks 6. The dynamic bandwidth allocation apparatus 12 calculates, based on the reception rates of the upstream frames F1 and F2 from the optical network units 2, the sending rates of relay destinations of the upstream frames F1 and F2, and changes in the amounts of data occurring upon relaying the upstream frames F1 and F2, allocated bandwidth upper limits (max_bw) at which even when the amounts of data increase, the upstream frames F1 and F2 can be relayed; and dynamically allocates amounts of upstream transmission for the respective optical network units 2 in the range of the calculated allocated bandwidth upper limits (max_bw).

Abstract: An optical communication system, where in an optical transmission apparatus arranged on a transmission side of respective repeating sections, an OSC optical amplifier is provided on an OSC light optical path between from an OSC transmitter to a multiplexer, and the OSC optical amplifier is controlled so that the power of OSC light transmitted on the transmission path becomes a previously set target value. As a result the OSC light is amplified by a different amplifying device to that for the main signal lights at the time of transmission. Therefore even in the case where the span losses are large, OSC light can be reliably received by the optical transmission apparatus on the reception side.

Abstract: An optical device that includes multiple optical modulators having target operating wavelengths that are distributed over a band of wavelengths and actual operating wavelengths is described. For example, the target operating wavelengths of adjacent optical modulators may be separated by a wavelength increment. Moreover, because of differences between the actual operating wavelengths and the target operating wavelengths of the optical modulators, tuning elements may be used to tune the optical modulators so that the actual operating wavelengths match corresponding carrier wavelengths in a set of optical signals. Furthermore, control logic in the optical device may assign the optical modulators to the corresponding carrier wavelengths based at least on differences between the carrier wavelengths and the actual operating wavelengths, thereby reducing an average tuning energy associated with the tuning elements.

Abstract: Systems and methods for identifying a fault location in an optical network are disclosed. In accordance with one embodiment of the present disclosure, a method for identifying a fault location in an optical network comprises monitoring, by a network element, an eastward optical path and a westward optical path for faults. The method further comprises transmitting, by the network element, a first data packet along the eastward path and a second data packet along the westward path. The first and second data packets comprise an eastward fault indicator and a westward fault indicator comprising information associated with any eastward or westward faults occurring on the eastward or westward paths. The fault indicators indicate the existence of an eastward or westward fault and the network element that detected the fault.

Abstract: A method of distinguishing a wavelength-dependent reflective element (HRD) from wavelength-independent events in an optical network, the reflective element (HRD) being highly-reflective at a first predetermined wavelength (?1) and significantly less reflective at least one other predetermined wavelength (?2), comprising the steps of: connecting the wavelength-dependent reflective element (HRD) to said optical path at a first position, and, using an optical time domain reflectometer (22) connected to said optical path at a position remote from said reflective element, launching into said optical path light at said first wavelength (?1) and at said second wavelength (?2), detecting corresponding backreflected light from said optical paths and obtaining therefrom first and second OTDR traces (OTDR-?1, OTDR-?2) corresponding to said first (?1) and second (?2) wavelengths, respectively, of detected backreflected light as a function of optical distance from said point; comparing the first and second OTDR traces to