Abstract: An appropriate ring topology is selected by searching network topology information on the basis of given information about client signal paths on a predetermined condition, and a wavelength ring accommodating the client signal paths and having an optimal transmission characteristic is designed on the basis of the selected ring topology. Accordingly, accommodation of client signal paths in an optical network is efficiently designed.

Abstract: Provided are a photonic cross-connector system, a wavelength division multiplexing (WDM) system using the photonic cross-connector system, and an optical communication network based on the WDM system. The photonic cross-connector system includes: an optical coupler branching an input optical signal into a plurality of paths; a wavelength selective switch (WSS) extracting at least one wavelength signal from the input optical signal and outputting the extracted wavelength signal to at least one port; a WDM multi-casting apparatus simultaneously copying and reproducing the input optical signal into different wavelengths and changing modulation methods of the input optical signal into different types of modulation methods; an optical transmitter and/or receiver branching and coupling the input optical signal; and a control system controlling the optical coupler, the WSS, the WDM multicasting apparatus, and the optical transmitter and/or receiver.

Abstract: A Centralized Resource Management (CRM) system that supports the sharing of all the transponders in a WXC node, i.e., any spare transponder can be reconfigured to accommodate any drop channel, regardless of wavelength or input port. Consequently, network restoration in case of network failures is supported as well as the ability to reconfigure as a result of dynamic traffic requirements in the network. CRM advantageously is applied to conventional WXC node as well as WSS-based WXC nodes in the WDM networks. Three CTM schemes which manage the transponders in the WSS-based WXC node are described along with reconfiguration algorithms for an optical switchless CRM solution.

Abstract: An optical transmission system capable of time difference correction without lengthening guard times, thereby improving optical packet transmission efficiency. A switching processor sets identical switching timing for input ports thereof such that signals input from the input ports are switched at the same timing. When an optical dummy packet is received, the switching processor switches the optical dummy packet to be returned to the originating node. A time difference corrector detects synchroneity of the switched and looped-back optical dummy packet and, if asynchronism is detected, varies readout timing until synchroneity is attained, thereby correcting the time difference so that the optical dummy packet may fit in the switching time range and thus can be switched normally.

Abstract: Methods for controlling lasers or other light emitting devices to compensate for performance degradations due to temperature changes and aging without disrupting the transmission of information are presented. Disclosed embodiments describe various methods of applying mathematical models and digital signal processing algorithms to continuously calculate and execute precise output power adjustments. A synthesized test signal is injected into the normal data stream is applied to the laser system. The magnitude of the test signal is sufficiently small that it is buried in system noise and will not alter the noise margin of the signal or the transmitted data. Micro-detection, recovery and digital signal processing of the embedded test signal produces precisely monitored output power and modulation amplitude measurements used to accurately adjust performance characteristics regardless of temperature or age.

Abstract: In a method and arrangement for forming reception pulses, output signals of an upstream comparator which recognizes light pulses are used to evaluate a downstream arrangement and are newly formed and emitted as pulses. The aim is to produce a method and an associated circuit arrangement for forming reception pulses which represent a saving in energy, whereby said arrangement can be integrated into existing receiver systems, requires no external time base and can work with the signal of an upstream comparator. In a first step, an input signal delivered by an upstream comparator is delayed, whereupon a time reference is produced in a controlled manner and an output pulse begins to be formed in a controlled manner by means of the delayed input signal from the first step. The input signal level is examined once production of the time reference is completed.

Abstract: The present invention provides a colorless multiplexing system and method for detecting new optical channels at power levels below that which would cause data errors in existing traffic, and on top of background light, thus, overcoming a known risk inherent in colorless multiplexing—that a channel of the same wavelength as an existing channel is incorrectly added to the original working, traffic-carrying, channel's path.

Abstract: A system and method for a cell switching optical network. A block of data is buffered at an edge node and sliced into data slices. Slice headers are pre-appended to each data slice. The data slices are then scheduled for transmission onto an optical switching network during fixed time slots defined on a per carrier wavelength basis.

Abstract: The invention provides an optical shutter (400) for a communication system of a type comprising first (B1, B2) and second (A1, A2) communication paths along which information-bearing radiation propagates in opposite directions. The shutter (400) comprises: an optical tap (440) and a power monitor (430) for monitoring power of information-bearing radiation propagating along the first path (B1, B2) and for generating a corresponding radiation power indicative signal; a control unit (420) for comparing the indicative signal with a threshold value to generate a control signal (control); and shutter switch (410) for selectively substantially transmitting or blocking radiation propagating along the second path (A1, A2) in response to the control signal.

Abstract: A data distribution system transmitting and receiving a large capacity of data such as image data smoothly without incurring a delay over an optical fiber line located between a data sever and a client device. In the data transmission system, a plurality of client devices are bus-connected through an optical fiber to a data server transmitting and receiving data as signal light. Each of the client devices has a client optical switch and is connected with a client access device. The client optical switch is structured with a thermal-lens forming element and a signal-light path shifting member. When any of the client devices forwards an access command to its own client access device, control light is irradiated from the client access device to the own client optical switch thus effecting a switchover. Thus, transmission data of from the data server is stored in a data storage of the relevant client device.

Abstract: Methods and systems for controlling optical power attenuation are provided. A method comprises periodically measuring an optical power of an optical signal received by an optical receiver and periodically measuring a first attenuation control signal voltage. When the optical power measurement is outside a target power range, the method continues with calculating a target voltage necessary to maintain the optical power measurements at a target power level; calculating a second attenuation control signal based on the target voltage, wherein the second attenuation control signal is calculated to provide an over-damped transient response that maintains the second attenuation control signal within a usable range of a variable optical power attenuator; applying a second attenuation control signal voltage based on the second attenuation control signal to the variable optical power attenuator; and adjusting attenuation of the optical signal based on the second attenuation control signal voltage.

Abstract: An all-optical converter (10) for converting an intensity-modulated optical signal into an optical signal modulated to the DPSK format, includes a first input (152a) for a first intensity-modulated optical signal (12), a differential encoding module (100) adapted to perform a differential encoding between the first signal (12) and a second optical signal synchronous with the first signal (12), a device adapted to modulate (200) the phase of an optical signal (16) according to the differential encoding performed by the differential encoding module (100), and an output (162c) of the device adapted to modulate (200) delivering an optical signal modulated to the DPSK format (14).

Abstract: In an optical transmission device, when wavelength division multiplexed light formed from signals of a plurality of wavelengths are received, an optical signal of one wavelength comprised in this wavelength division multiplexed light is planarized and non-signal light of the same wavelength is reproduced. The reproduced light is modulated with a transmission data string, an optical signal is generated, and a wavelength division multiplexed light comprising the generated optical signal is transmitted.

Abstract: A transponder in a wavelength division multiplexing apparatus detects a wavelength of a leak light (received light) having one of plural wavelengths multiplexed or divided by a WDM unit, the leak light having been received from the WDM unit when the transponder is connected to the WDM unit; determines a transmission wavelength which is a wavelength of a light to be transmitted to the WDM unit on the basis of the wavelength of the received light; and sets to convert the wavelength of the light to be transmitted to the WDM unit into the transmission wavelength, and transmit the converted light.

Abstract: An optical packet switch switches optical packets according to bit-rates at which the optical packets are provided. For example, optical packets that are received at similar bit-rates may be routed to a destination at separate time slots over a single channel wavelength, and optical packets that are received at different bit-rates may be routed to the destination over separate channel wavelengths. When optical packets are provided at different bit-rates on a plurality of input paths, optical packets provided at low bit-rates may be compacted before switching to the destination. Alternatively or additionally, the bit-rates of the optical packets may be balanced before switching to the destination. Bandwidth contention among optical packets may be resolved by polarizing optical packets originating from separate input paths in different polarization directions, and merging optical packets having different polarization directions onto a single switched channel wavelength.

Abstract: An optical transmission apparatus has a first wavelength selective switch (WSS) for route switching, provided with respect to each route, to selectively output signal light from a first input route to second through Nth output routes and to selectively output signal lights from second through Nth input routes to a first output route, for every wavelength, a second WSS for add and drop, to selectively output a signal light from an add port to the first through Nth output routes via the first WSS for every wavelength, and to selectively output the signal lights from the first through Nth input routes to a drop port via the first WSS for every wavelength, and an optical coupler to multiplex each of the signal lights output from the first WSS to the output routes and each of the signal lights output from the second WSS to the output routes, for every route, and to send multiplexed signal light to a first WSS of an other route, and to branch and supply multiplexed signal light input from said other route to the fi

Abstract: In a system for data communication between an information terminal to be operated by a user and remote communication nodes, the present invention intends to suppress the power consumption of the information terminal. For that purpose, communication nodes 2, 3 and 4 each emit diffuse light carrying a pilot signal blinking at a low frequency to notify the presence of the communication node and an ID signal belonging to a higher frequency range, the ID signal containing inherent address etc. for identifying each communication node. A mobile phone 1 as the information terminal captures an image and processes the image data to detect the pilot signal of each communication node. Then, determining the position of each node and setting a limited range for reading the pixels around that position, the mobile phone 1 reads the detection signals of the pixels within the limited range at high speed and obtains identification information.

Abstract: The invention provides for optical circulators which redirect light from port to port sequentially in one direction used to separate traffic in a bidirectional optical fiber transmission system. The invention provides for using two optical circulators in each span of bidirectional fiber so that the OSC channel can be transmitted in one direction opposite to the WDM channels. The invention also provides for a gigabit Ethernet path between chassis which is utilized for control traffic and customer traffic. The invention is placed in a non-critical region of the optical spectrum and is independent of all other chassis equipment. The invention also provides the advantage in alternate embodiments of providing the option of a second counter propagating WDM channel being transmitted along with the OSC to provide additional system capacity. The invention also provides the advantage in an alternate embodiment of allowing the OSC to be amplified through a raman source without the need of complete system retrofit.

Abstract: A system and method for detecting and compensating for thermal drift in an optical network in a manner that enables an increased number of optical channels to be used on a given optical medium, such as on a single optical fiber. A pair of narrow band, closely spaced optical signals from an optical transmitter function as a “temperature probe” signal. The two narrow band signals are centered within one passband of a filter of an optical device, such as an optical router. When the two narrow band signals are transmitted back to an optical receiver via the router, the magnitudes of the two signals are compared and a determination can be made as to the magnitude and direction of thermal drift of the passbands of the filter of the optical router.

Abstract: A device that accepts input of asynchronously-arriving variable-length optical packets transmitted over a plurality of lightpaths, and outputs same to a single optical path, comprising: in order to prevent the optical packets from overlapping in the output lightpath, a controller that uses the delay times of the delay elements and the optical packet length and arrival gap time thus read to determine by computation the delay element used for temporary storage, where a plurality of stages of processors is provided. Thus, the processing required to determine the delay time is performed by parallel processing with the results of processing the prefix-sum operation used in parallel pipelined processing along with the queue length, optical packet length and arrival gap time of the buffering device.