AFourieranalysisappliedtotheMach–Zehnderinterferometer(MZI)transmissionspectrumforsimultaneousrefractiveindex(RI)andtemperaturemeasurementsisproposedandexperimentallydemonstratedinthisLetter.InthefastFouriertransform(FFT)spectrumoftheMZItransmissionspectrum,severalfrequencycomponentsaregenerallyobserved,whichmeansthatthetransmissionspectrumoftheMZIisformedbythesuperpositionofsomedual-modeinterference(DMI)spectra,andeachfrequencycomponentrepresentsdifferentcore-claddinginterferences.WecanselectsomedominantfrequencycomponentsintheFFTspectrumoftheMZItransmissionspectrumtotaketheinverseFFT(IFFT).Then,thecorrespondingDMIpatternscanbeobtained.DuetotheshiftofthewavelengthoftheseDMIspectrawithchangesintheenvironmentalparameters,wecanusethecoefficientmatrixoftheseDMIspectraformulti-parametersensing.InthisLetter,twoDMIpatternsareseparatedfromtheresultanttransmissionspectrumoftheMZI.AstheRIandtemperaturechange,theshiftsofthetwoDMIpatternswithrespecttotheRIandtemperaturewillbeobserved.ThesensitivitiesoftheRIandtemperatureare-137.1806nm∕RIU(RIunit)and0.0860nm∕°C,and-22.9955nm∕RIUand0.0610nm∕°CforthetwoDMIs.Accordingly,itcanbeusedtosimultaneouslymeasureRIandtemperaturechanges.Theapproachcaneliminatetheinfluenceofmultipleinterferencesandimprovetheaccuracyofthesensor.
