Abstract: A local area network is used to interconnect media equipment, such as telephones, VoIP telephones, a media server, etc., located at geographically distributed sites of an optical communication system. The local area network may be implemented within an optical services channel carried by a WDM optical communication link. This may provide the needed connectivity at low costs and may allow conference calls to be accommodated.

Abstract: An optical wavelength-division-multiplexing (WDM) network has at least one transit node, where a majority of received channels are destined for a remote node, and at least one hub node, where a majority of received channels are switched to a local destination. The network follows a channel-level protection scheme, and at least one of the nodes has a cross-connect switch of a tandem design with a wavelength switch portion optically positioned in a feedback path of a space switch portion. Alternatively, the transit node has a tandem switch design, where the space switch interfaces with the network fibers, and the hub node has at least a wavelength switch that interfaces with the network fibers. The capacities of the respective wavelength and space switch portions of the tandem cross-connect are configured according to the expected ratio of local traffic to passthrough traffic.

Abstract: An apparatus and method for reducing polarization hole burning in a rare-earth-doped fiber amplifier within an optical communication system by converting an optical carrier having a characteristic wavelength into a polarization-rotating optical carrier is disclosed. The apparatus includes a polarization-fixing device optically coupled in the optical transmission system to transform the optical carrier to a polarized optical carrier, and an acousto-optic modulator positioned to receive a first portion of the polarized optical carrier and to orthogonally convert the polarization of the polarized optical carrier and to shift the polarized optical carrier by a modulation frequency. The apparatus and method further includes a polarization beam combiner optically coupled to receive the orthogonally polarization converted and frequency shifted polarized signal and a portion of the original polarized optical carrier.

Abstract: An optical wavelength-division-multiplexing (WDM) network has at least one transit node, where a majority of received channels are destined for a remote node, and at least one hub node, where a majority of received channels are switched to a local destination. The network follows a channel-level protection scheme, and at least one of the nodes has a cross-connect switch of a tandem design with a wavelength switch portion optically positioned in a feedback path of a space switch portion. Alternatively, the transit node has a tandem switch design, where the space switch interfaces with the network fibers, and the hub node has at least a wavelength switch that interfaces with the network fibers. The capacities of the respective wavelength and space switch portions of the tandem cross-connect are configured according to the expected ratio of local traffic to passthrough traffic.

Abstract: An improvement in the reliability of an optical communication system comprising two optical fiber lines, a first transmitter for transmitting at least a signal in the first optical line, a second transmitter for transmitting at least a signal in the second optical line, at least one two-stage-amplifier in each of said first and second line, laser pumps providing pumping signals to said stages of the amplifiers, a first receiver for receiving the signal from the first optical line, and a second receiver for receiving the signal from the second optical line, wherein said laser pumps form a single system that provides a first pumping signal to at least one stage of said at least one amplifier of each of said first and second line.