Lucent Technologies Inc.

Bruce Lee Nelson

Mohammad Taghi Fatehi

Kamal Kumar Raychaudhuri

James E Ballintine

Wilhelm Kremer

A scalable, reconfigurable, and cost-effective add/drop arrangement is provided which enables a wavelength division multiplexed (WDM) system to be upgraded to accommodate new or changing add/drop requirements without disruptions in existing service. The add/drop arrangement is based on a modular architecture wherein one or more modular optical routing devices are coupled in an optical fiber path to facilitate the selective adding/dropping of individual optical channels and to facilitate in-service upgrades without disrupting existing transmissions in the optical fiber path. In an exemplary embodiment, at least two directional optical transfer devices, such as optical circulators, are coupled to a drop path for dropping optical channels from the WDM signal, an add path for receiving optical channels to be added to the WDM signal, and a common path between the directional optical transfer devices. In the common path, at least one optical routing module is employed which is capable of receiving the WDM signal at an input and routing or otherwise switching the WDM signal to outputs, each of which can be coupled to one or more wavlength-selective modules. Each wavelength-selective module can be configured with an arrangement of optical filters, such as fiber gratings, and optical switches to facilitate the selective adding and dropping of one or more individual optical channels. Importantly, the optical routing module includes additional outputs for coupling to additional optical routing modules, additional wavelength-selective modules, and other components in order to accommodate changing add/drop requirements, which is an anticipated characteristic especially of metropolitan optical networks.

Scalable add/drop architecture for lightwave communication system

Automatic reduction of optical signal power supplied by an upstream network element by a prescribed amount is achieved by capturing and processing reflected optical energy that is generated within the optical fiber path as a result of a downstream fiber cut, open connector, or other potentially hazardous discontinuity. Generally, the power level of the reflected optical signal is detected and measured in the optical fiber path and the optical signal power supplied by the upstream network element is automatically reduced. The optical signal power may either be reduced by an amount corresponding to the measured reflected optical signal power or may be completely shut off until the faulty condition is resolved. In one illustrative embodiment, an apparatus for automatically reducing or shutting off the optical signal power supplied by an upstream network element includes a directional optical transfer device disposed along the optical fiber path and coupled to the output of a network element, an optical power monitor for measuring the reflected optical energy received via the directional optical coupler as a result of a downstream fiber discontinuity, and control circuitry coupled between the power monitor and the network element to control the optical signal power being supplied by the network element based on the monitored power level of the reflected optical signal. The control circuitry may be analog, digital, or may be implemented using a microprocessor operating under software or firmware program control.

Method and apparatus for controlling optical signal power in response to faults in an optical fiber path

A restoration procedure for use in bidirectional multiplex section-switched ring transmission systems re-establishes a connection path by using a loopback connection at nodes bordering the failure and by then establishing a jumpered connection path, for each active tributary affected by the failure. The jumpered connection path at affected node eliminates any unnecessary loop formed in the re-established connection path caused by the loopback connection at the border nodes. There is stored in memory at each node (1) the provisioned connection path, (2) the jumpered path, and (3) a jumper flag is set indicating that a jumper connection exists. When the failure is cleared the (1) jumpered path is removed and its record erase from memory, (2) the provisioned connection path is restored, and (3) the jumper flag is reset. Advantageously, the this operation can be programmed into existing node controllers and is compatible with existing restoration procedures.

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Middletown, NJ, United States of America

Bruce Lee Nelson