简介：Anovelarchitectureforthecolorlessopticalnetworkunit(ONU)isproposedandexperimentallydemonstratedwithdirect-detectionopticalorthogonalfrequencydivisionmultiplexing(DDO-OFDM).Inthisarchitecture,polarization-divisionmultiplexingisusedtoreducethecostatONU.Inopticallineterminal(OLT),quadratureamplitudemodulation(QAM)intensity-modulatedOFDMsignalwithx-polarizationat10Gbit/sistransmittedasdownstream.AteachONU,theopticalOFDMsignalisdemodulatedwithdirectdetection,andy-polarizationsignalismodulatedforupstreamon-offkeying(OOK)dataat5Gbit/s.SimulationresultsshowthatthepowerpenaltyisnegligibleforbothopticalOFDMdownstreamandtheon-offkeyingupstreamsignalsafterover50kmsingle-modefiber(SMF)transmission.