Abstract:Inthispaper,anewresonantcavityenhancedphotodetector,whichisformedbythreecavities(filter,spacerandabsorptioncavity)isproposedandexperimentallytestified.Itsresponsespectrallinewidthisonlydeterminedbythefiltercavity,whichisless4nm;itsquantumefficiencyisdeterminedbytheabsorptioncavity,andthenewphotodetectorsresponsecancompensatethelossofthefiltercavitytosomeextent.