Two-fiber optical shared protection ring with a bi-directional 4 x 4 optical switch fabric

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 NxN optical switch fabric system disposed in the node. The NxN 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. Each three-port optical device includes a bi-directional port coupled to an I/O port. The bi-directional port is configured to propagate the at least one bi-directional channel.