中英文翻译--RF和微波光纤设计指引.doc

RFandMicrowaveFiber-OpticDesignGuideAgereSystemsInc.,throughitspredecessors,begandevelopingandproducinglasersanddetectorsforlinearfiber-opticlinksnearlytwodecadesago.Overtime,theseoptoelectroniccomponentshavebeencontinuallyrefinedforintegrationintoavarietyofsystemsthatrequirehighfidelity,highfrequency,orlong-distancetransportationofanaloganddigitalsignals.Asaresultofthiswidespreaduseanddevelopment,bythelate1980s,theselinkproductswereroutinelybeingtreatedasstandardRFandmicrowavecomponentsinmanydifferentapplications.Thereareseveralnotableadvantagesoffiberopticsthathaveledtoitsincreasinguse.Themostimmediatebenefitoffiberopticsisitslowloss.Withlessthan0.4dB/kmofopticalattenuation,fiber-opticlinkssendsignalstensofkilometersandstillmaintainnearlytheoriginalqualityoftheinput.Thelowfiberlossisalsoindependentoffrequencyformostpracticalsystems.Withlaseranddetectorspeedsupto18GHz,linkscansendhigh-frequencysignalsintheiroriginalformwithouttheneedtodownconvertordigitizethemforthetransmissionportionofasystem.Asaresult,signalconversionequipmentcanbeplacedinconvenientlocationsoreveneliminatedaltogether,whichoftenleadstosignificantcostandmaintenancesavings.Savingsarealsorealizedduetothemechanicalflexibilityandlightweightfiber-opticcable,approximately1/25theweightofwaveguideand1/10thatofcoax.Manytransmissionlinescanbefedthroughsmallconduits,allowingforhighsignalrateswithoutinvestinginexpensivearchitecturalsupports.Theplacementoffibercableisfurthersimplifiedbythenaturalimmunityofopticalfibertoelectromagneticinterference(EMI).Notonlycanlargenumbersoffibersbetightlybundledwithpowercables,theyalsoprovideauniquelysecureandelectricallyisolatedtransmissionpath.Thegeneraladvantagesoffiber-opticsfirstledtotheirwidespreaduseinlong-hauldigitaltelecommunications.Inthemostbasicformoffiber-opticcommunications,lightfromasemiconductorlaserorLEDisswitchedonandofftosenddigitallycodedinformationthroughafibertoaphotodiodereceiver.Bycomparison,inlinearfiber-opticsystemsdevelopedbyLucent,thelightsentthroughthefiberhasanintensitydirectlyrelatedtotheinputelectricalcurrent.Whilethisplacesextrarequirementsonthequalityofthelasersandphotodiodes,ithasbeenessentialinmanyapplicationstotransmitarbitraryRFandmicrowavesignals.Asaresult,tensofthousandsofAgereSystemstransmittersarecurrentlyinuse.Theinformationofferedhereexaminesthebasiclinkcomponents,providesanoverviewofdesigncalculationsrelatedtogain,bandwidth,noise,anddynamicrangeanddistortion.Asectiononfiber-opticcomponentsdiscussesanumberofkeyparameters,amongthemwavelengthandloss,dispersion,reflections,andpolarizationandattenuation.Additionalinformationevaluatesopticalisolators,distributed-feedbacklasersandFabry-Perotlasers,predistortion,andshort-vs.long-wavelengthtransmission.OneoflinearopticalfiberrelationmainusagesorreceivesbetweentheelectronicinstallationandtheremotelocalizationantennainthetransmissiontransmitsRFandthemicrowavesignal。Becauseoftheopticalfiberchainflexibility，possiblycanforthesimulationordigitalsignaldesignsomeantennas，includingthemilitaryandthecommercialcommunicationssatellite，thegloballocalizationsatellite，theremotesensingwithtracesthelighthouse，orwirelesscellnetwork。Anotherkindoftypechainistheopticalfiberdelayline，installsinapackageitincludingatransmitter，areceiver，withlongtextilefiber。Itmayprovidethelongdelaytime,highbandwidth,withlowweight.Thesehigh-frequencyRFandthemicrowaveproducthasobtainedbenefitsfromtheuselinearopticalfiberequipmentcabletelevisionragingtidemiddleearth.Inhere,thetextilefiberexpandstheTVsignalthetransmittingrange,improvestheirqualityandthesystemreliability,butwhenmerelyonlyhastheelectriccable,evenwiththesystemwhichusedcompareshassavedtheexpenseIneachoftheseapplications,aswellasmanyothers,theAgereSystemstransmittersandreceiverscomprisingthelinksaresimilarandcanbetreatedasstandardmicrowavecomponents.Focusingonthesecommonelements,thisdesignguidedescribesthegeneraltechnicalconsiderationsandequationsnecessaryforengineerstochoosethemostappropriateAgereSystemscomponentsfortheirsystems.Theseequationsalsohavebeenincorporatedintovariousprograms,whichanAgereSystemsapplicationsengineercanusetoprovideananalysisforaspecificlinkapplication.Figure1showsthethreeprimarycomponentsinafiber-opticlink:anopticaltransmitter,afiber-opticcable,andanopticalreceiver.Inthetransmitter,theinputsignalmodulatesthelightoutputfromasemiconductorlaserdiode,whichisthenfocussedintoafiber-opticcable.Thisfibercarriesthemodulatedopticalsignaltothereceiver,whichthenreconvertstheopticalsignalbacktotheoriginalelectricalRFsignal.RF和微波光纤设计指引大概二十年以前，Agere系统公司通过其前辈开始发展和生产激光和检测器线性光纤的联系。这些电子元件组成部分连续不断地为了进入各种各样要求高保真，高频率，或者长途模拟和数字的信号的运输的系统。由于这广泛传播的使用和发展，八十年代末，这些系列产品通常被认为是标准的RF和微波组成部分不同的应用。光纤的许多引人注意的优势使它被越来越广泛的应用。光纤设备的最主要的好处是其损失低。由于光的减弱的小于0.4dB每公里，光纤传送的信号几乎可以传输数十公里并且仍然保持原来的输入的质量。对于最实际的系统低的纤维损失也是独立的频率。用激光和检测器加速到18GHz，联系能以他们原来的形式发送高频信号，无须改变或者为了一个系统的传输部分使他们数字化。因此，信号转化设备便可以闲置或者干脆不用，这样便可以节省一部分费用。机械的灵活性节省了费用，同时，轻量级光纤电缆，大约只有1/25波导的重量的1/10coax。考虑到高的信号速率没有昂贵的建筑投资方面的支持。许多传播线能通过小的导管支持。光缆的布局更进一步被光纤的自然免疫性简化到电磁的干扰(EMI)。不仅数目大的纤维能用电源电缆严紧地捆扎，他们也提供了一个独一的安全和电气隔离的传输路径。纤维光学设备的巨大的优势首先使得他们在长的拖曳数字电讯中的广泛传播中被使用。按光纤通信的最基本的形式，从一种半导体激光器发射的光或者发光二极管发射的光通过一种纤维发送数字编码的信息到一个光电二极管。通过比较，在线性的纤维光学系统中发展朗讯，光通过纤维发送的强度直接与输入的电流有关。然而这就对激光和光电二极管的质量有额外的要求，它在许多传送专断RF和微波信号应用中很重要。因此，目前有成千上万的Agere系统的传输器在被使