Thebasicideaofthefiniteelementbeampropagationmethod(FE-BPM)isdescribed.Itisappliedtocalculatethefundamentalmodeofachannelplasmonicpolariton(CPP)waveguidetoconfirmitsvalidity.Boththefielddistributionandtheeffectiveindexofthefundamentalmodearegivenbythemethod.Theconvergencespeedshowstheadvantageandstabilityofthismethod.Thenaplasmonicwaveguidewithadielectricstripdepositedonametalsubstrateisinvestigated,andthegroupvelocityisnegativeforthefundamentalmodeofthiskindofwaveguide.Thenumericalresultshowsthatthepowerflowdirectionisreversetothatofphasevelocity.
