简介：ThisLetterpresentsamethodofanopticalsensorformeasuringwavelengthshifts.Thesystemconsistsofadiffractiongratingandatotalinternalreflectionheterodyneinterferometer.Asaheterodynelightbeamstrikesagrating,thefirst-orderdiffractionbeamisgenerated.Thelightpenetratesintoatotalinternalreflectionprismatananglelargerthanthecriticalangle.Awavelengthvariationwillaffectthediffractiveangleofthefirst-orderbeam,thusinducingaphasedifferencevariationofthelightbeamemergingfromthetotalinternalreflectionsinsidethetrapezoidprism.Boththeexperimentalandtheoreticalresultsrevealthat,forthefirst-orderdiffractivebeam,thesensitivityandresolutionlevelsaresuperiorto5°/nmand0.006nm,respectively,intherangeofwavelengthfrom632to634nm,andaresuperiorto3.1°/nmand0.0095nmintherangefrom632to637nm.Forthetheoreticalsimulationofthefourth-orderdiffractivebeam,theyaresuperiorto6.4deg∕nmand0.0047nmintherangefrom632to637nm.