简介：Photoniccrystalfibers(PCFs)withasteppedraised-coreprofileandonelayerequallyspacedholesinthecladdingareanalyzed.Usingeffectiveindexmethodandconsideringaraisedsteprefractiveindexdifferencebetweentheindexofthecoreandtheeffectiveindexofthecladding,weimprovethecharacteristicparameterssuchasnumericalapertureandV-parameter,andreduceitsbendinglosstoaboutonetenthofaconventionalPCF.ImplementingsuchastructureinPCFsmaybeonestepforwardtoachievelowlossPCFsforcommunicationapplications.

简介：SpecimensofPbTesinglefilmaredepositedonGesubstratesbyvacuumthermalevaporation.Duringthetemperaturerangeof80–300K,thetransmittanceofaPbTefilmwithin2–15μmismeasuredevery20KbythePerkinElmerFouriertransforminfraredspectroscopycryogenictestingsystem.Then,therelationshipbetweentherefractiveindexandwavelengthwithin7–12μmatdifferenttemperaturesisreceivedbythefullspectruminversionmethodfitting.ItcanbeseenthattherelationshipconformstotheCauchyformula,whichcanbefitted.Then,therelationshipbetweentherefractiveindexofthePbTefilmandthetemperature/wavelengthcanbeexpressedasn(λ,T)=5.82840-0.00304T+4.61458×10~(-6)T~2+8.00280∕λ~2+0.21544∕λ~4,whichisobtainedbythefittingmethodbasedontheCauchyformula.Finally,thedesignedvalueobtainedbytheformulaandthemeasuredspectrumarecomparedtoverifytheaccuracyoftheformula.

简介：Basedontotalreflectionprinciple,acompactliquid-refractiveindexmeasuringequipmentwasdesignedandfabricated,inwhichadiodelaserwasusedaslightsourceandacharge-coupleddevice(CCD)asphotodetector.Theinfluenceonmeasurementaccuracyofthewavelengthshiftandintensityfluctuationofthediodelaserweresurmountedbyaneffectivefeedbackmethod.Itiscrucialwhetherthediodelasercouldbeusedinsuchasystem.

简介：Byusingagraded-indexmultimodefiber(GI-MMF)witharelativelyflatindexprofileandhighrefractiveindexofthefibercore,amicroextrinsicfiber-opticFabryProtinterferometric(MEFPI)strainsensorisfabricatedthroughchemicaletchingandfusionsplicing.Higherreflectanceofthemicrocavityisobtainedduetotheless-curvedinnerwallinthecenterofthefibercoreafteretchingandhigherindexcontrastbetweentheGI-MMFcoreandair.Themaximumreflectionofthesensorisenhanced12dBthanthatobtainedbyetchingoftheEr-orB-dopedfibers.Highfringecontrastof22dBisobtained.ThestrainandtemperatureresponsesoftheMEFPIsensorsareinvestigatedinthisexperiment.Goodlinearityandhighsensitivityareachieved,withwavelength-strainandwavelength-temperaturesensitivitiesof7.82pm/μεand5.01pm/°C,respectively.

简介：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.