Abstract: The present invention is directed to a protection switch for use in a node of a two-fiber optical shared protection ring. The two-fiber optical shared protection ring propagates at least one bi-directional channel. Each bi-directional channel includes a working first wavelength signal and a working second wavelength signal. One fiber in the two-fiber optical channel shared protection ring propagates the working first wavelength signal in a first direction and the other fiber in the two-fiber optical channel shared protection ring propagating the working second wavelength signal in a second direction opposite the first direction. The switch includes an N×N optical switch fabric system disposed in the node. The N×N optical switch fabric includes 2N input/output (I/O) ports, wherein N is four, or an integer multiple of four. Each optical switch fabric is configured to switch at least one bi-directional channel. At least N three-port optical devices are coupled to N of the I/O ports.

Abstract: A two-fiber ring architecture capable of carrying multiple wavelength channels and allowing client self-healing of single point failures. The ring architecture includes a two-fiber optical ring carrying at least one wavelength channel, wherein the wavelength channel has working traffic and protection traffic. The optical ring can include a single ring, two interconnected rings, or multiple interconnected rings. Specifically, the ring architecture includes a first client networking element connected to the optical ring by a first pair of 2×2 add drop matrices and a second client networking element connected to the optical ring by a second pair of 2×2 add drop matrices. At least one interconnect node is also provided when more than one ring is used, wherein the interconnect node has a first 2×2 interconnect matrix and a second 2×2 interconnect matrix.

Abstract: The present invention is directed to a protection switch for use in a node of a two-fiber optical shared protection ring. The two-fiber optical shared protection ring propagates at least one bi-directional channel. Each bi-directional channel includes a working first wavelength signal and a working second wavelength signal. One fiber in the two-fiber optical channel shared protection ring propagates the working first wavelength signal in a first direction and the other fiber in the two-fiber optical channel shared protection ring propagating the working second wavelength signal in a second direction opposite the first direction. The switch includes an N×N optical switch fabric system disposed in the node. The N×N optical switch fabric includes 2N input/output (I/O) ports, wherein N is four, or an integer multiple of four. Each optical switch fabric is configured to switch at least one bi-directional channel. At least N three-port optical devices are coupled to N of the I/O ports.

Abstract: An optical cross-connect system provides 4×4 switching matrices and self-healing from any single point of failure. The switching matrices route working traffic and redundant protection traffic between a plurality of client network elements and an optical ring. The system also has a client interface for transporting the working traffic and the protection traffic between the switching matrices and the client network elements. The optical cross-connect system further includes a ring interface for transporting the working traffic and the protection traffic between the switching matrices and the optical ring. The switching matrices are structured so that protection is provided from single point failures by electrical switching at the client network element location. This significantly reduces the need for optical switching within the matrices.

Abstract: A wavelength selective optical cross-connect includes a first demultiplexor feeding into individually removable modules that in turn feed a first multiplexor, such that the cross-connect is expandable and repairable on a wavelength or waveband basis. The modules desirably include multiple optical components in the optical path, with components in each module matched to others in that module to provide module-to-module variation below that of the variation in module components. The modules desirably include an additional demultiplexor and multiplexor. The modules also desirably include wavelength or narrowband amplification together with power equalization. The modules may also include a switch fabric.

Abstract: An optical channel shared protection ring including multiple ring nodes, the nodes including optical switch or crossbar capability for performing ring switching for end-node protection switching for wavelengths that may be dropped and added and a non-intrusive optical channel monitor at least on each working channel both on the add and drop side of the node, such that a monitor is always present at both a head-end location where traffic is introduced to the ring and at a tail end location where traffic leaves the ring, so as to be able to trigger end-node protection switching performed by the head-end and tail-end nodes based on the condition of absence of adequate signal at the tail-end location alone, and not on the condition of absence of adequate signal at both the head-end and the tail-end location, thus avoiding unnecessary protection switching.

Abstract: Long delays in bidirectional multiplex section-switched self-healing ring transmission systems are avoided by eliminating looping of communications signals when restoring them in response to a failure in the ring and by distributing switching of paths to be protected to ring nodes other than those immediately adjacent the failure. This is realized by provisioning each node in the bidirectional multiplex section-switched ring transmission system with a map of its traffic pattern (all active tributaries) and the relative position of each ring node in the ring transmission system, and allowing the ring node, if it has communications traffic affected by the failure, to bridge and switch to and from the protection path.