Tropic Networks Inc.

Nortel Networks Corporation

Alcatel Lucent

Alcatel-lucent USA Inc.

Colin Geoffrey Kelly

Derrick Remedios

Ping Wai Wan

Matthew D Brown

Eddie Kai Ho Ng

James Benson Bacque

Paul David Obeda

Alan Glen Solheim

Patrick Chilufya Chimfwembe

Robert Michael Bierman

Chris Knapton

Xiang Liu

Peter Steven Pieda

Chung Y Wu

Song Jiang

John Frederick Groves

Phil Campbell

Tony Bitzanis

Alex Ngi

We disclose a modular fiber-interconnect device that can be used in a ROADM to optically interconnect wavelength-selective switches and optical add/drop blocks thereof. An example module of the modular fiber-interconnect device has seventeen optical ports, each implemented using an MPO connector of the same type. The number of (nominally identical) modules in the modular fiber-interconnect device depends on the degree N of the ROADM and can vary, e.g., from two for N=4 to fourteen or more for N&#x2265;20. A proper set of duplex optical connections within the ROADM can be created in a relatively straightforward manner, e.g., by running MPO cables of the same type from the wavelength-selective switches and the optical add/drop blocks of the ROADM to appropriate optical ports of the various modules of the modular fiber-interconnect device.

Fiber-management solution for an optical-network node

One embodiment provides a network node of a metro optical network that includes first and second optical filters. The first optical filter is configured to pass wavelength channels in a first wavelength band and block wavelength channels in a non-overlapping second wavelength band. The second optical filter is configured to block wavelength channels of the first wavelength band and pass wavelength channels of the second wavelength band. An optical splitter is configured to split a received optical signal into first and second signal portions and to direct the first signal portion to the first optical filter. An optical combiner is configured to combine output of the second optical filter with the second signal portion from the optical splitter. An optical transceiver is configured to recover data from a first wavelength channel passed by the first optical filter, and to output a second wavelength channel passed by the second optical filter.

Flexible ROADM-less optical hub and spoke node architecture for coherent transponders

For wavelength division multiplexing (WDM) communications, apparatus and methods are provided for performing tone-based optical channel monitoring that is less sensitive to stimulated Raman scattering (SRS). In tone-based optical channel monitoring, in which WDM channels are modulated with one or more tones, detecting and measuring the tone power is commonly used as a measure of signal power in each channel. In WDM systems with long fiber spans and high signal powers, however, SRS tends to transfer energy from shorter wavelengths to longer wavelengths, whereby the tones are no longer accurately indicative of the signal power of the individual wavelength channels. Apparatus and methods are provided which reduce the effect of SRS by filtering the monitored WDM signals into sub-bands and detecting each sub-band independently.

Apparatus and method for improving the tolerance of tone-based optical channel monitoring to stimulated Raman scattering

A method and apparatus for distributed measurement of chromatic dispersion in an optical network is disclosed. The network comprises optical switching nodes interconnected by optical links. An optical link may comprise multiple spans, each span ending in a transport module which comprises signal-processing components. At least one optical switching node has a probing signal generator transmitting an optical probing signal along a selected path in the network. Probing-signal detectors placed at selected transport modules determine chromatic-dispersion values and send results to a processing unit which determines appropriate placement of compensators or appropriate adjustments of compensators placed along the path. A preferred probing signal has the form of wavelength modulated optical carrier which is further intensity modulated by a periodic, preferably sinusoidal, probing tone. Variation in the phase-shift of the probing tone corresponding to variation of the wavelength of the optical probing signal determines chromatic-dispersion characteristics for different spans of the path.

Method and system for distributed measurement and compensation of chromatic dispersion in an optical network

A protocol independent multiplexer is described that allows for multiple different protocols that operate at different bit rates to be combined and output in a format that may have yet another bit rate. The multiplexer includes a series of inputting devices that are each coupled to a respective buffering device, a mapping device coupled to each of the buffering devices, and an outputting device coupled to the mapping device. Each of the inputting devices receive an input optical signal and forwards recovered data information to the corresponding buffering device. The buffering devices store the data information and output to the mapping device, the outputting being controlled by the mapping device to ensure that the buffering devices remain approximately half full. The mapping device formats the data information into individual data units and outputs the data units to the outputting device which subsequently multiplexes the data units. One key advantage of this protocol independent multiplexer is that only one piece of hardware is required for the operation of numerous different protocols.

Protocol independent sub-rate device

A method and system for identification of a channel in an optical network is provided. The channel is identified by the use of unique combinations of two or more low frequencies, or tones, modulated onto the channel and optionally, a network parameter associated with the channel.

Method and system for identification of channels in an optical network

A method and system for multi-level power management in an optical network is provided. They include three levels of power management. The first level of power management dynamically changes equipment settings in each module of equipment so that required module setpoint values in each module are achieved. The second level of power management determines module setpoint values for each module of equipment within each node in the optical link so that required node setpoint values are achieved. The third level of power management determines node setpoint values at each node in the optical link so that the optical link meets predetermined power specifications. If any of the three levels cannot achieve the required setpoint values, an error signal is generated by that level of power management and sent to the level of power management above it, thus initiating a higher level of power management. As a result, a dynamic and automatic adjustment to changing operating conditions and configurations in the network is provided, which allows to maintain relatively stable network powers. Each level of power management is implemented such that sections of the network can operate independent of each other, thus increasing the survivability of the network.

System and method for power management in an optical network

A method and system for compensating for side effects of cross gain modulation in amplified optical networks, which allows reliable identification of expected and unexpected channels in the network is provided. Each optical channel traveling in the optical network is marked with a unique channel signature (expected channel signature), having one or more dither tone modulated onto the optical channel; followed by detecting a spectrum of tones, including said modulated dither tones and ghost tones thereof produced by the cross gain modulation in the optical network, at various locations in the optical network. Amplitudes of the spectrum tones, which belong to the expected channel signature, are compared with a first threshold, while amplitudes of the remaining spectrum tones, which are not the valid tones, are compared with a second threshold, which is lower than the first threshold. The spectrum tones are identified as valid tones if their amplitudes are above the first threshold; and an alarm signaling that the expected channel signature is missing is generated if the amplitude of the spectrum tone is below the first threshold. Yet another alarm is generated signaling that an unexpected channel is detected in the network if the amplitude of at least one of the remaining spectrum tones is exceeding the second threshold. Alternatively, the other alarm is generated if amplitudes of the remaining spectrum tones belonging to one of the allowable channel signatures in the network are above the second threshold. A corresponding system incorporating the step of the methods described above is also provided.

Method and system for compensating for side effects of cross gain modulation in amplified optical networks

The present invention involves the passing of clock information from a point where a tributary payload is mapped into a carrier to a point where a tributary payload is de-mapped from the carrier. A synchronization signal is generated at the mapping end. Rather than sending clock phase information implicitly by means of the data, as is normally the case, a value of the synchronization signal at a given time, is sent explicitly, independent from the payload data.

Asynchronous payload mapping using direct phase transfer

A method for determining locations and gain settings of optical amplifiers in an optical network is provided. The method comprises evaluating allowable amplifier locations and successively eliminating selected locations until no further locations can be eliminated without the network violating predetermined specifications. This systematic method is applicable to a variety of network topologies and takes into account existing network limitations. In one embodiment, the method for determining the locations and gain settings of the amplifiers uses the amount of operating margin in the network to select locations to be eliminated. In another embodiment, the method is repeated a number of times with different selections of amplifier locations, and the method providing the arrangement with the least number of amplifiers is chosen.

Method for determining locations and gain settings of amplifiers in an optical network

A method for determining locations and gain settings of amplifiers in an optical network is provided. The method comprises evaluating allowable amplifier locations, randomly generating sets of amplifier locations from the allowable amplifier locations, and applying genetic operations to the sets of amplifier locations until a predetermined exit condition is satisfied. This systematic method is applicable to a variety of network topologies and takes into account existing network limitations. In one embodiment, the method for determining the locations and gain settings of the amplifiers uses the amount of operating margin in the network to select sets of locations to be eliminated. In another embodiment, the method takes into account and determines the placement of dispersion compensation modules (DCMs), choices of which are provided by DCM placement procedures.

Method for determining location and gain settings of amplifiers in an optical network by using a genetic algorithm

Apparatuses and methods are provided for chromatic dispersion compensation of wavelength division multiplexed (WDM) optical signals within an optical add/drop multiplexer (OADM) and especially within a remotely reconfigurable add/drop multiplexer (RROADM). The arrangement is especially useful in metro or regional networks where RROADMs can be dynamically reconfigured to deliver signals from any node to any other node. A dispersion compensation module (DCM) is located in the multiplexed through path of the RROADM between the drop module and the add module such that only wavelengths passing through the RROADM are compensated and shorter optical paths traversing only one span between adjacent nodes are not compensated. This allows lower cost static DCMs to be used, allows more flexibility in DCM values and allows fewer DCMs to be used while maintaining dispersion limits.

Reconfigurable optical add/drop multiplexer with buried dispersion compensation module

Devices and methods are provided for a re-configurable optical add/drop multiplexer (ROADM) having a static circulator, a selectable grating and a reversible circulator. The use of a reversible circulator in a known optical drop multiplexer configuration allows the selectable grating to be used for selecting both the add-wavelength and the drop-wavelength while maintaining an East/West architectural split to allow for SONET compliant maintenance. This invention provides a cost-effective enhancement to a duplex reflective wavelength selective ROADM.

Duplex reflective re-configurable optical add/drop multiplexers

A method and system for determining location and value of dispersion compensating modules (DCMs) in an optical network is provided. The method comprises evaluating possible DCM values and locations and successively adding selected combinations to the network until the dispersion limits of the network are met. This systematic method is applicable to a variety of network topologies. In one embodiment, the method for determining the location and value of the DCMs uses the amount of compensated effective dispersion over all lightpaths that pass through the DCM to select the combinations. In another embodiment, the method is repeated a number of times with different selections of DCM value and location combinations, and the method providing the least number of DCMs and the lowest DCM values is chosen.

Growing community of inventors

Ottawa, Canada

Colin Geoffrey Kelly