Self-organizedIn0.5Ga0.5As/GaAsquantumislandstructureemittingat1.35μmatroomtemperaturehasbeensuccessfullyfabricatedbymolecularbeamepitaxy(MBE)viacycled(InAs)1/(GaAs)1monolayerdepositionmethod.Photoluminescence(PL)measurementshowsthatverynarrowPLlinewidthof19.2meVat300Khasbeenreachedforthefirsttime,indicatingeffectivesuppressionofinhomogeneousbroadeningofopticalemissionfromtheIn0.5Ga0.5Asislandsstructure.Ourresultsprovideimportantinformationforoptimizingtheepitaxialstructuresof1.3μmwavelengthquantumdot(QD)devices.