Wavelength division multiplexed optical communication system having a reconfigurable optical switch and a tunable backup laser transmitter

Abstract

In a WDM optical communication system that includes a plurality of nodes interconnected by communication links, a node is provided that includes a reconfigurable optical switch having a plurality of input ports and at least one output port. The node also includes a plurality of transmitters that are each coupled to one of the input ports of the optical switch. Each of the transmitters generate an information-bearing optical signal at a different channel wavelength from one another. The reconfigurable optical switch is adaptable to receive at any of the input ports any of the channel wavelengths at which the plurality of transmitters operate and direct the channel wavelengths to the output port. At least one backup transmitter is coupled to one of the input ports of the optical switch. The backup transmitter includes a tunable laser tunable to any of the channel wavelengths at which the plurality of transmitters operate. The reconfigurable optical switch includes at least one wavelength selective element that selects at least one channel wavelength from among any of the channel wavelengths received at any of the input ports. The switch also includes a plurality of optical elements associated with the wavelength selective elements, Each of the optical elements direct one of the selected channel wavelengths selected by the associated wavelength selective element to the output port independently from every other channel wavelength. The selected channel wavelengths directed to the output port are combined on the output port.

Description

STATEMENT OF RELATED APPLICATION[0001]This application is a continuation of U.S. patent application Ser. No. 10 / 099,561, filed Mar. 15, 2002, entitled “Wavelength Division Multiplexed Optical Communication System Having A Reconfigurable Optical Switch And A Tunable Backup Laser Transmitter,” which claims the benefit of U.S. Provisional Patent Application No. 60 / 276,310, filed Mar. 16, 2001, entitled “Reconfigurable Optical System.”FIELD OF THE INVENTION[0002]The invention relates generally to wavelength division multiplexed optical communication systems, and more particularly, to wavelength division multiplexed optical communication systems which include reconfigurable optical switches coupled to backup transmitters that incorporate tunable lasers.BACKGROUND OF THE INVENTION[0003]Wavelength division multiplexing (WDM) has been explored as an approach for increasing the capacity of fiber optic networks to support the rapid growth in data and voice traffic applications. A WDM system e...

AI Technical Summary

Problems solved by technology

Consequently, adding or decreasing the number of optical channels or changing the channel wavelength or spacing is not possible without providing a completely new demultiplexing switching element to the optical network.

In other words, the scalability of such networks is limited because of the switching element's lack of flexibility.

One area where this lack of flexibility manifests itself is in connection with the provisioning of a backup path through the network in the event of equipment failure.

For example, in the aforementioned WDM transmission system, since each channel wavelength is assigned its own path through the switching element, it is not possible to reroute a given channel wavelength along a different path should a failure occur in the transmitter that generates the given wavelength.

In particular, it is not possible to substitute for the failed transmitter a backup transmitter that resides on another of the switching element's input ports unless the backup transmitter operates on its own channel wavelength that is different from the wavelength at which the failed transmitter operates.

Unfortunately, the provisioning of a backup path can be a slow process requiring inter-node communication and processing, which not only slows down the restoration process, but which may also disturb other traffic in the system.

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