circuits in terrestrial networks, with a single-fiber capacity greater than the amount
of traffic that currently needs to terminate at any single node [1].
These advances in transmission technology make it desirable for systems to
have optical add/drop capability. Exploiting the inherent wavelength granu larity of
WDM, an optical add/drop multiplexer (OADM) allows some WDM channels
(also referred to as wavelengths) to be dropped at a node, while the others traverse
the same node without electronic regeneration. Previously, it was necessary to
terminate line systems at each node served, and then regenerate the wavelength
signals destined for other nodes. The ability to optically add/drop a fraction of a
system’s wavelengths at a node was first achieved ...