Protection switching in bidirectional WDM optical communication networks with transponders

A system for protection switching in a wavelength division multiplexed optical communication network including optical transponders within optical nodes comprising:

• an optical communication network including a plurality of optical nodes, each optical node including means for adding and dropping an optical channel from an optical waveguide configured to carry wavelength division multiplexed optical communication signals;
• a first work optical transponder positioned to receive a first work optical channel dropped by the optical add-drop multiplexer, the first work optical transponder including receiving means for converting the dropped work optical channel to an electrical signal and transmitting means for generating a short-reach optical signal modulated with information from the dropped work optical channel;
• a second work optical transponder positioned to add a work optical channel to the optical add-drop multiplexer, the second work optical transponder including a work optical transmitter for creating a work optical channel to be added to a wavelength division multiplexed optical signal carried by the optical waveguide and a receiving means for receiving a short-reach optical signal modulated with information to be placed on the work optical channel to be added;
• a first protect optical transponder positioned to receive a protect optical channel dropped by the optical add-drop multiplexer, the first protect optical transponder including receiving means for converting the dropped protect optical channel to an electrical signal and transmitting means for generating a short-reach optical signal modulated with information from the dropped protect optical channel;
• a second protect optical transponder positioned to add a protect optical channel to the optical add-drop multiplexer, the second protect optical transponder including an optical transmitter for creating a protect optical channel to be added to a wavelength division multiplexed optical signal carried by the optical waveguide and a receiving means for receiving a short-reach optical signal modulated with information to be placed on the protect optical channel to be added;
• means for detecting the strength of the optical channel received by the first work optical transponder;
• control means responsive to the means for detecting the strength of the optical channel received by the first work optical transponder, the control means activating the second protect transponder and inactivating the second work transponder when the strength of the optical channel received by the first work optical transponder falls below a preset level.