简介:Inthispaper,wederivethebrightanddarkphotonnumberstatesforspatialinterferenceoftwoormorelightbeamsandsucceedintheexplanationofYoung'sinterferenceexperiment,andalsoachieveabettercomprehensionofthewellknowncommentofDirac"eachphotononlyinterferenceswithitself".Fromthefullyquantumpointofview,theoriginoftheinterferencefringesconsistsinthemodetransformationandthedetectionofdouble-slitstates.
简介:Anexperimentofadaptivepolarizationmodedispersion(PMD)compensationfor40-Gb/sreturn-to-zero(RZ)opticalcommunicationsystemisreported.Intheexperiment,degreeofpolarization(DOP)isusedasfeedbacksignalandparticleswarmoptimization(PSO)methodisadoptedaslogiccontrolalgorithm.Thecompensationtimeisabout200ms,thecompensateddifferentialgroupdelay(DGD)isupto30ps,andbiterrorrate(BER)of10^-9isreachedwhenPMDcompensationisemployed.
简介:Anewscreen-spotimagingmethodbasedonopticalmeasurementisproposed,whichisapplicabletotheclose-rangemeasurementofaircraft'sthree-dimensional(3D)attitudeparameters.Lasertrackerisusedtofinishtheglobalcalibrationsofthehigh-speedcamerasandthefixedscreensontestsite,aswellastoestablishmedia-coordinate-framesamongvariouscoordinatesystems.Thelasercooperationobjectmountedontheaircraftsurfaceprojectslaserbeamsonthescreensandthehigh-speedcamerassyn-chronouslyrecordthelight-spots'positionchangingwithaircraftattitude.Therecordedimagesequencesareusedtocomputetheaircraftattitudeparameters.Basedonthematrixanalysis,theerrorsourcesofthemeasurementaccuracyareanalyzed,andthemaximumrelativeerrorofthismathematicalmodelisestimated.Theexperimentalresultshowsthatthismethodeffectivelymakesthechangeofaircraftpositiondistinguishable,andtheerrorofthismethodisnomorethan3′whiletherotationanglesofthreeaxesarewithinacertainrange.
简介:WhenfemtosecondlaserpulsesinterferewithchirpedfemtosecondlaserpulsesinAs2S3fiber,achirpedfibergratingisformed.Ananalyticalexpressionisgiventodescribethechirpedgrating,anditsBraggreflectivityiscalculated.BecauseofthehighphotosensitiveeffectofAs2S3material,thechirpedfibergratinghasawideBraggreflectivespectrumandhighreflectivitybychoosingproperparameters.Thisindicatesthatthechirpedfibergratingcanbeusedasastretcherinthefemtosecondchirpedpulseamplification(CPA)system.
简介:ByusingPDM-OFDM-16QAMmodulation,all-Ramanamplification,coherentdetection,and7%forwarderrorcorrection(FEC)threshold,wesuccessfullydemonstrate63-Tb/s(368×183.3-Gb/s)signalover160-kmstandardsinglemodefiber(SSMF)transmissionintheC-andL-bandswith25-GHzchannelspacing.368opticalchannelswithbandwidthspacingof25GHzaregeneratedfrom16externalcavitylasersources.After160-kmSSMFtransmission,alltestedbiterrorrate(BER)areunder3.8×10-3,whichcanberecoveredby7%FECthreshold.Withineachchannel,weachievethespectralefficiencyof6.85bit/s/HzinC/Lband.
简介:Aquasi-cycliclow-densityparitycheck(QC-LDPC)codeisconstructedbyanimp
简介:Weexperimentallydemonstrateall-opticalclockrecoveryfor100Gb/sreturn-to-zeroon–offkeyingsignalsbasedonamonolithicdual-modedistributedBraggreflector(DBR)laser,whichcanrealizebothmodespacingandwavelengthtuning.Byusingacoherentinjectionlockingscheme,a100GHzopticalclockcanberecoveredwithatimingjitterof530fs,whichisderivedbyanopticalsamplingoscilloscopefromboththephasenoiseandthepowerfluctuation.Furthermore,fordegradedinjectionsignalswithanopticalsignal-to-noiseratioaslowas4.1dBanda25kmlongdistancetransmission,good-qualityopticalclocksareallsuccessfullyrecovered.
简介:Anovelmethodfordistortion-freeopticalpulsetransmissionistheoreticallyproposedandsimulated,inwhichtwotimelensesformedbydispersionfibersandquadraticphasemodulationsareutilized.OneisusedasanopticalinverseFouriertransformation(OIFT)devicetotransformtheinitialtime-domaindatatofrequency-domainoneatthetransmitterandtheotherasanopticalFouriertransformation(OFT)devicetorecoverthedataatthereceiver.Byusingtheunchangedspectralenvelopeinlinearopticalfibercommunication,theinitialdatacanberecovered.Throughsimulations,a10×100Gb/sintensitymodulateddirect-detection(IM-DD)densewavelengthdivisionmultiplexing(DWDM)systemover2000kmtransmissionwithoutthecompensationforpolarizationmodedispersion(PMD)anddispersionslopeisachieved,whichcanbeusedtoupgradethecurrent10-Gb/sIM-DDsystemtoa100-Gb/sonedirectly.
简介:A100-Gb/shigh-speedopticaltransmitterisproposedandexperimentallydemonstrated.Basedonfrequency-quadruplingtechnique,twosub-channelswithafixed50-GHzspacingareobtainedfromonelasersource.Usingreturn-to-zerodifferentialquadraturephase-shiftkeying(RZ-DQPSK)modulationformatandpolarizationmultiplexing(PolMux),onlylow-speedelectronicdevicesof12.5GHzareneededforthe100-Gb/stransmitter.Thiseliminatestheneedofultrahigh-speedoptoelectronicdevicesandthusgreatlyreducesthecost.Theexperimentalresultsshowthatthistransmittercanachievegoodperfor-manceindispersiontoleranceofa25-kmsinglemodefiber(SMF).
简介:相位测量偏折术(PMD)是一种结合光线反射原理和条纹相位编码的光学面形检测方法,具有设备简单、成本低廉、稳定抗干扰等优点。但传统的偏折术需要对透明元件后表面进行黑化或粗糙化处理,以避免后表面反射对条纹相位提取的干扰,过程中可能损伤光学表面。分析了PMD面形检测方法用于透明元件检测的数学模型,提出了一种基于多频条纹反射和谱估计算法的新型PMD——多频条纹偏折术,分离了透明元件前后表面反射信号。从数字信号分析角度描述了谱估计方法分离精度的影响因素,并给出了分离结果优化的具体方案。进行了数值模拟和实验验证,取得了与基于相移的传统PMD非常接近的检测结果,证明了多频条纹偏折术的正确性和可行性。实验结果表明,该技术具有精度高、无需改变现有实验装置和待测元件的优点,为透明元件的无损静态检测提供了可靠的方法。
简介:Alowcost8×10-Gb/stransmissionsystemover1500kmonconventionalfiberusingchirpedfiberBragggrating(CFBG)asdispersioncompensatorisdemonstrated.Thebiterrorrate(BER)below10-10at1500kmisobtained.Thechannelspacingis0.8nmandtheopticalamplifierspacingis100km.Only16erbium-dopedfiberamplifiers(EDFAs)areused.
简介:Non-uniformstep-sizedistributionisimplementedforsplit-stepbasednonlinearcompensationinsingle-channel112-Gb/s16quadratureamplitudemodulation(QAM)transmission.Numericalsimulationsofthesystemincludinga20×80kmuncompensatedlinkareperformedusinglogarithmicstepsizedistributiontocompensatesignaldistortions.50%ofreductioninnumberofstepswithrespecttousingconstantstepsizesisobserved.Theperformanceisfurtherimprovedbyoptimizingnonlinearcalculatingposition(NLCP)incaseofusingconstantstepsizeswhileNLCPoptimizationbecomesunnecessarywhenusinglogarithmicstepsizes,whichreducesthecomputationaleffortduetouniformlydistributednonlinearphaseforallsuccessivesteps.
简介:Weexperimentallydemonstratea4-Gb/sradio-over-fiber(RoF)systemwith40-kmfiberand2-mwirelessdistancedownstreamat100-GHzcarrier.Tothebestofourknowledge,thisisforthefirsttimeinChinatorealizeopticalwirelesslinkat100GHz.Inthisletter,simpleintensitymodulatorwithdirectdetector(IM-DD)modulationisemployedandopticalpowerpenaltyafter40-kmsinglemodefiber(SMF)-28and2-mairlinkis3.2dBwithbit-error-rate(BER)at1×109.