System and methods for upgrading an optical add-drop multiplexer (OADM) to higher degree wavelength selective router (WSR)/wavelength selective switch (WSS) are disclosed. For example, an OADM of degree-2 may be provisioned for upgrades to degree-3 and higher. The existing links power and signal-to-noise...http://www.google.com/patents/US7343096?utm_source=gb-gplus-sharePatent US7343096 - Method and apparatus for in-service upgrading of OADM to wavelength selective switch of higher degree
