Labeling of signals in optical networks and its applications

The paper is a review and comparative analysis of most common techniques proposed to attach additional data or identification information to digital signals in optical fiber networks by purely optical means. Such "labels" or "headers" can be attached either to continuous bit streams, e.g., in SDH networks or to optical packets. They enable to monitor, route and identify signals in transparent optical networks, especially those with optical wavelength multiplexing, allow management and supervision of remote optical amplifiers and can be used in optical switching systems. Other applications of this relatively unknown technology include monitoring of optical path dispersion, equalization of channels in DWDM systems and detection of intrusion or jamming in highly secure networks.