Wereportonacompactpassivemode-lockedEr:fiberringlaseroperatedatthefundamentalrepetitionrateof517MHz,whichwebelieveisthehighestfundamentalrepetitionrateeverreportedinaringcavityfiberlaser.Thekeytechniqueistheemploymentoftwoinnovativehigh-powerwavelengthdomainmultiplexercollimatorswithallgainfibercavitysuitedforthehighpower(upto2W)pumping.Thelaserisfeaturedwithadirectchirpfreeoutputpulse,whichis97fswithoutextracavitycompressionatanaverageoutputpowerof90mW.