Fortransmission,allsevenchannelsareloadedintotherecirculatingloopcomprisedofthreespans,all-EDFAamplification, andnoopticaldispersioncompensation.Eachspanisidentically configured with either MDF, SMF, or LAF fiber and is nominally 90 km. Table I lists the fiber parameters. We circulate the data in the loop six times for a total transmission distance of ∼1600 km. Once transmitted, the data are unloaded from the loopandthecenterchannelisopticallyfiltered(1nm),andthen, detected by a Picometrix coherent receiver, and then, digitized