06381045 is referenced by 12 patents.
Dual concentric core fiber is used for optical communication. Inbound messages lying in a first wavelength channel are received from a terminal portion of the fiber, and outbound messages lying in a second such channel are injected into the terminal portion. The optical fiber has at least one annular portion surrounding a central core portion. The inbound messages are received from the annular portion, and the outbound messages are injected into the central core portion. Alternatively, the inbound messages are received from the central core portion, and the outbound messages are injected into the annular portion.