Lucent Technologies Inc.

Jds Uniphase Corporation

Other

Daniel Yousef Al-Salameh

David S Levy

David J Dougherty

Gaylord W Richards

Wenhua Lin

Nathan Myron Denkin

Wilhelm Kremer

Steven H Hersey

Timothy Owen Murphy

Wei-Chiao William Fang

Mario F Alvarez

Gabriela Livescu

Anastasios Tzathas

Nicholas Paul DeVito

William Joseph Gartner

Philip M Francisco

Jithamithra Sarathy

Donald L Husa

Maria F Mendez

A method and apparatus for monitoring spectral tilt uses an arrayed waveguide grating (AWG) to separate a multiplexed optical signal having a plurality of wavelength channels into a plurality of sub-bands, where each sub-band spans a different wavelength range and includes more than one wavelength channel. A photodetector array is provided to measure the optical power in each of the sub-bands, while control electronics calculate spectral tilt of the multiplexed optical signal using the measured optical power in each of the sub-bands. The spectral tilt monitor in accordance with the instant invention provides spectral resolution, increased monitoring speeds, and decreased manufacturing costs.

Spectrally resolved fast monitor

A facility is provided to allow a supervisory message to quickly propagate through a transmission network without delay. Specifically, a supervisory message is quickly routed from one node to a next node by (a) splitting the control channel signal carrying the supervisory message at a receiving node, (b) sending one of the split control channel signals to an output via switchable apparatus for immediate transmission the next node and (c) sending the other split signal to a controller for analysis. If the controller invokes a predetermined procedure as a result of the content of the message, e.g., invokes protection switching, then the controller forms a supervisory message identifying the invoked procedure, operates the switchable apparatus so that the message identifying the invoked procedure may be routed to the output in place of the split channel signal message.

Control channel processor and switching mechanism

An optical transmission system formed from a plurality of nodes interconnected in a ring configuration via at least two transmission media provides protection capacity for each optical channel. If a channel signal does not meet predetermined criteria, then a loss of signal indication is declared for the channel and one of a plurality of protection switching states is invoked to re-route service traffic carried by the impaired channel to its destination via corresponding protection capacity. The switching states include particular transmission states and at least &ldquo;keep-alive&rdquo; and &ldquo;protection access&rdquo; states.

Shared optical protection ring architecture

Vulnerability of an optical network to channel impairments or the like, is addressed by utilizing real-time monitoring and control of prescribed optical channel impairments. The impairments are compensated for by employing an optimization process in the optical network such that the optical signals from the source or sources of the impairments are controllably adjusted at any particular node in the network. The optical signals are attenuated more or less at the source node of the associated optical channel in order to optimize performance of the corresponding optical channel in the network. A variable optical attenuator (VOA) is used at the &lgr; laser source of optical channel having the impairment to obtain the attenuation. The optical signal impairment is measured at a receiving node and the source node of the associated optical channel is determined. Then, a control message is transmitted to the identified source node indicating that a VOA associated with the corresponding optical channel &lgr; laser source is to be adjusted to insert more or less attenuation as the case may be. This process is iterated until the corresponding optical channel yields optimum performance for the impairment being measured. A VOA in a remote node associated with the &lgr; laser source of the associated optical channel is first adjusted. Then, a VOA in the local node associated with the optical channel being monitored is adjusted to further optimize the prescribed metric of the optical channel being monitored. This adjustment is iterated until the performance of the associated channel is optimized.

Optical transmission system including performance optimization

An optical filter/combiner arrangement is used for filtering and combining optical signals in at least two wavelength bands supplied by at least two respective Wavelength Division Multiplexed (WDM) systems along the same optical fiber. More specifically, optical signals received by the optical filter/combiner arrangement from an optical fiber are appropriately filtered so that optical signals in one wavelength band are processed by components of one WDM system and optical signals in another wavelength band are processed by components in another WDM system. After processing by the respective WDM system components, the optical signals in each of the wavelength bands are then re-combined and supplied along the same optical fiber. By using the optical filter/combiner arrangement, existing WDM systems can be upgraded to higher capacity using the existing optical fiber and without replacing existing components or disrupting existing service.

Apparatus and method for upgrading the capacity of wavelength division multiplexed optical networks

An optical communications system employs a plurality of optical nodes interconnected in a ring configuration by at least two optical transmission media, for example, optical fiber. The at least two optical transmission media, in this example, provide optical service transmission capacity and optical protection transmission capacity. Efficient restoration of optical communications between optical nodes in the ring, after an optical transmission media failure, is realized by employing a relatively simple and efficient optical switch matrix having a first number of possible switching states and, then, by utilizing only a second number of the switching states fewer than the first number to switch optically from the optical service transmission capacity of the failed or faulted optical transmission media to the optical protection transmission capacity of another optical transmission media. Optical switching states of the optical switch matrix are blocked that are not actively used for switching from the active optical service capacity of the faulted optical transmission media to the standby optical protection capacity of the other optical transmission media. Use of this relatively simple optical switch matrix allows for the bulk switching of the optical wavelengths as contrasted with the one-to-one switching of the optical wavelengths used in prior arrangements.

Optical transmission system including optical restoration

Optical-to-electrical and electrical-to-optical signal conversion is substantially eliminated for performance of monitoring and maintenance functions within a wavelength-division-multiplexed optical network having a Network Control Element by detecting optical intensities of signals conveyed over wavelength channels at the optical layer. Values associated with the detected optical intensities are generated and conveyed to the Network Control Element. The Network Control element analyzes these values for the purposes of fault detection, channel power monitoring, channel signal to noise ratio determinations, channel continuity checks, and network provisioning.

Optical monitoring apparatus and method for network provisioning and maintenance

An optical communications system employs a plurality of optical nodes interconnected in an optical ring transmission configuration by at least two optical transmission media, for example, optical fiber. The at least two optical transmission media, in this example, provide optical service transmission capacity and optical protection transmission capacity. Efficient restoration of optical communications between optical nodes in the optical ring transmission configuration, after an optical transmission media failure, is realized by employing an autonomous optical restoration arrangement and technique. To this end, each node autonomously controls an optical switch matrix in the node in effecting the desired restoration without the need of switch control signals transmitted from any other node in the ring, from a main controller or from a central controller.

A bi-directional protection facility is provided in an optical communication system in which an optical communications node communicates with another optical communications node via first and second bi-directional communications paths respectively serving as a service path and protection path, and in which a filter at each node processes signals respectively received over the service and protection paths and generates an in-band signal and out-of-band signal for each of the paths. A control unit then generates a Loss of Signal indication for the service path if the level of the out-of-band signal is found to be greater than the level of the in-band signal and protection switching is effectuated as a function of the presence of the control signal. In addition, an outgoing signal to the other communications node is interrupted for a sufficient period of time to cause a LOS at that node and thus trigger protection switching thereat to complete the bi-directional switching process.

Optical protection switch employing an interference filter

A pair of SONET rings (12' and 14') can be interworked by providing at least two gateways (16.sub.m-1 and 16.sub.m) that are shared by each of the rings. Each shared gateway has the capability of transferring a block of optical information resident in a prescribed time slot in an interchange frame associated with one ring to a time slot in an interchange frame associated with the other ring so the block reaches its intended destination in that ring.

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Marlboro, NJ, United States of America

Daniel Yousef Al-Salameh