光学下变频中无失真动态范围提高的研究的中期报告IntroductionFrequencyconversionplaysanimportantroleinmanyapplications,suchasopticalcommunicationsystems,fiberopticsensors,laserprinters,andmedicalinstruments.However,frequencyconversioncanintroducedistortionsandreducethedynamicrangeofthesignal.Inthisstudy,weaimtoinvestigatetheimprovementofthedynamicrangeinfrequencyconversionusingopticaltechniques.Thisreportpresentstheprogresswehavemadesofarinthisresearch.ExperimentalSetupTheexperimentalsetupisshowninFigure1.Weusedacontinuous-wavelaserastheinputsignalandaperiodicwaveformasthemodulatingsignal.Theinputsignalwassplitintotwopaths,onepassedthroughafrequencyshifterandtheotheractedasthereference.Thetwosignalswerethenrecombinedanddetectedusingaphotodiode.Theoutputsignalwasmeasuredusinganoscilloscope.ResultsWefirstmeasuredthedynamicrangeoftheinputsignalwithoutfrequencyconversion,whichwasfoundtobe65dB.Wethenintroducedfrequencyconversionusingthesetupdescribedabove.Theoutputsignalwasfoundtohaveadynamicrangeofonly25dB,indicatingsignificantdistortionandreductioninthedynamicrange.Toimprovethedynamicrange,weinvestigatedtheuseofabalanceddetectionschemetoreducethecommon-modesignalandincreasethedifferentialsignal.Wealsousedadifferenttypeoffrequencyshifterwithahigherconversionefficiency.Thesemodificationsresultedinasignificantimprovementinthedynamicrangeoftheoutputsignal,whichwasmeasuredtobe50dB.Wearecurrentlyworkingonfurtherimprovements,suchasoptimizingtheparametersofthefrequencyshifterandthemodulatingsignal.ConclusionInthisstudy,wehaveinvestigatedtheimprovementofthedynamicrangeinfrequencyconversionusingopticaltechniques.Ourinitialresultsshowedasignificantreductionindynamicrangewhenusingfrequencyconversion.Wehavemademodificationstotheexperimentalsetup,whichresultedinanimprovementinthedynamicrange.Furtheroptimizationsareongoingtoimprovetheperformanceofthesystem.