Bidirectional wavelength-division-multiplexed passive optical network

A bidirectional wavelength division multiplexed passive optical network (WDM-PON) comprising:

• a central office (CO) that transmits and receives multiplexed optical signals;
• a remote node (RN) that communicates with the CO, receives a multiplexed optical signal to demultiplex, and receives a demultiplexed optical signal to multiplex;
• an optical network unit (ONU) that transmits and receives demultiplexed optical signals to and from the RN;
• operational and protective backbone optical fibers that connect the CO to the RN;
• and
• operational and protective distribution optical fibers that connect the RN to the ONU,
• wherein the ONU transmits and receives optical signals through the operational distribution optical fiber and the operational backbone optical fiber, and when a failure occurs in the operational distribution optical fiber or the operational backbone optical fiber, the ONU transmits and receives optical signals through the protective distribution optical fiber and the protective backbone optical fiber, and
• wherein the CO comprises:
• a first optical transceiver that transmits and receives optical signals;
• a 1×N arrayed waveguide grating (AWG) that wavelength-division multiplexes the optical signal transmitted from the first optical transceiver and wavelength-division demultiplexes the optical signal received into the first optical transceiver;
• a first broadband light source that provides a seed light for generating an optical signal to the ONU;
• a 2×2 optical coupler having ports at one end of the 2×2 optical coupler optically connected to a second WDM coupler and the first broadband light source, respectively, and having ports at the other end of the 2×2 optical coupler optically connected to the operational and protective backbone optical fibers, respectively;
• an optical isolator optically connected between the first broadband light source and the 2×2 optical coupler;
• a first WDM coupler and the second WDM coupler optically connected to each other, the first WDM coupler optically connected between the 1×N AWG and the second WDM coupler;
• an optical circulator optically connected between the first WDM coupler and the second WDM coupler;
• and
• a second broadband light source that is optically connected to the optical circulator and provides a seed light for generating an optical signal to the first optical transceiver, and
• wherein N represents a natural number.