简介:Asecondgenerationsolaradaptiveoptics(AO)systemisbuiltandinstalledatthe1-mNewVacuumSolarTelescope(NVST)oftheFuxianSolarObservatory(FSO)in2015.TheAOhigh-ordercorrectionsystemconsistsofa151-elementdeformablemirror(DM),acorrelatingShack–Hartmann(SH)wavefrontsensor(WFS)witha3500Hzframerate,andareal-timecontroller.ThesystemsawfirstlightonMar.16,2015.Thesimultaneoushigh-resolutionphotosphereandchromosphereimageswithAOareobtained.Theon-skyobservationalresultsshowthatthecontrastandresolutionoftheimagesareapparentlyimprovedafterthewavefrontcorrectionbyAO.
简介:Aterahertzexcitationsourcebasedonadual-lateral-modedistributedBraggreflector(DBR)laserworkinginthe1.5μmrangeisexperimentallydemonstrated.Byoptimizingthewidthoftheridgewaveguide,thefundamentalandthefirst-orderlateralmodesareobtainedfromthelaser.Themodespacingbetweenthetwomodesis9.68nm,correspondingtoabeatsignalof1.21THz.BytuningthebiascurrentsofthephaseandDBRsections,thewavelengthsofthetwomodescanbetunedby2nm,withasmallstrengthdifference(<5dB)andalargeside-modesuppressionratio(SMSR>45dB).
简介:A1.3-μmwavelengthvertical-mesaridgewaveguidemulitple-quantum-well(MQW)distributedfeedback(DFB)laserwithhighdirectlymodulatedbandwidthandwideoperationtemperaturerangeisreported.Withtheoptimizationofthestrained-layerMQWsintheactiveregion,thesurroundinggraded-indexseparated-confinement-heterostructurewaveguidelayers,togetherwiththeoptimizationofthedetuningandcouplingcoefficientoftheDFBgrating,highdirectlymodulationbandwidthof16GHzatroomtemperatureandwideworkingtemperaturerangefrom-40to85℃areobtained.Themeantimetofailure(MTTF)isestimatedtobeover2×10~6h.Thedeviceissuitableaslightsourceofhigh-bit-rateopticaltransmitterswithsmallsizeandreducedcost.
简介:Diode-pumpedpassivelyQ-switchedNd:GdVO4/Cr4+:YAGlaserswithasimpleflat-flatcavityweredemonstrated.Themaximumaverageoutputpowerat1.06μmwas1.25W.Thehighestpeakpowerandpulseenergywere7.56kWand75μJ,respectively,withthepulserepetitionrateof11.1kHzandpulsewidthof10nsattheincidentpumppowerof8W.
简介:Thecavitytuningcharacteristicsoforthogonallypolarizeddual-frequencyHe-Nelaserat1.15μmarepresented.Vectorial-extensionmodelbasedonsemi-classicallasertheoryrevealsthatcavitytuningcharacteristicsarerelatedtobeatfrequency,relativeexcitation,andtypeofNeisotope.Distortionsofcavitytuningcurvesbecomemoderatewiththeincreaseofbeatfrequencybecauseoftheweakeningofthecrosssaturationeffect.Distortionsareenhancedwiththeincreaseofrelativeexcitationbecauseofthecombinedactionoftheself-saturationandcross-saturationeffects.Byadoptingdual-isotopeNeinsteadofmonoiso-toplicNe,distortionsarereducedbecauseofthemisalignmentbetweenpeaksoftheself-saturationandnetgaincoefficients.Thetheoreticalcalculationsareingoodagreementwiththecorrespondingexperimentalresults.
简介:Aperiodicallypoledlithiumniobate(PPLN)opticalparametricgenerator(OPG)pumpedbyalaserdiode(LD)-pumpedQ-switchedTm,Ho:GdVO_4laseroperatedat2.048μmwithpumppulseof25nsandrepetitionrateof10kHzisreported.Acontinuoustunablemiddle-infrared(mid-IR)spectrumof3.88-4.34μmisobtainedbychangingthecrystaltemperaturefrom50to124°C.Whentheincidentpumppoweris3W,thetotalOPGoutputpoweris95mW,correspondingtoopticalconversionefficiencyof3.2%.
简介:AhighlyTm-dopedleadgermanateglassfiberisdevelopedusingtherod-in-tubemethod.The~2μmlaserbeamqualityofthefiberis~1.5.Theleadgermanatecompositefiberjumpersarehomemadeforallthefiberlaserinvestigations.Whencoreispumpedbya1590nmYb/Erfiberlaser,amaximumlaseroutputof313mWisachievedata670mWpumppower,andthecorrespondingslopeefficiencyis~52.8%.Moreover,byusinga2cmlongleadgermanatefiberasthegainmedium,a33mW1942nmTmlaserisalsodemonstrated.
简介:使用傅里叶变换光谱仪(FTIR)测试甚长波宽波段(6.4~15μm)红外探测器响应光谱的过程中,发现短波方向响应光谱异常。通过分步测试分析发现:探测器和放大器工作在非线性工作区导致某些情况下仪器信号发生饱和,引起了短波方向响应光谱畸变的现象。对FTIR测量甚长波宽波段(6.4~15μm)红外探测器响应光谱的畸变现象进行了分析,认为探测器的响应时间是影响其响应光谱的重要因素,并通过试验确定了测试系统对不同探测器所设置的测试参数,消除了响应光谱畸变的现象,并提高了测试准确度。
简介:我们求婚并且试验性地证明为M照振幅调整(正交调幅)追踪计划的一个通用、盲目的极化状态基于一个没有决定的指导半径的线性Kalman过滤器(RD-LKF)发信号。追踪性能的极化为调音的照阶段移动(QPSK)和16正交调幅信号通过模拟和实验被调查。静态的极化demultiplexing性能和动态追踪能力上的过滤器参数的影响经由模拟被讨论。在modulation-format-independent情形的过滤器参数的优化策略被建议,模拟被执行为QPSK,16QAM,和混合QPSK/16QAM信号评估极化demultiplexing惩罚。最后,建议没有决定的RD-LKF是试验性地,与经常的模量算法的各自的算法和为QPSK和16正交调幅和ultrafast极化追踪的优点的multimodulus算法相比,能力被证实。
简介:Ahigh-repetition-rateeye-safeopticalparametricoscillator(OPO),usinganon-criticallyphase-matchedKTPcrystalintracavitypumpedbyapassivelyQ-switchedNd:GdVO_4/Cr~(4+):YAGlaser,isexperimentallydemonstrated.Theconversionefficiencyfortheaveragepoweris7%frompumpdiodeinputtoOPOsignaloutputandtheslopeefficiencyisupto10.3%.Withanincidentpumppowerof7.3W,thecompactintracavityOPO(IOPO)cavity,operatingat15kHz,producesanaveragepowerof0.57Wat1570nmwithapulsewidthasshortas6ns.Thepeakpowerat1570nmishigherthan6.3kW.
简介:Enhanced2.7μmemissionisobtainedinEr3+/Tm3+andEr3+/Ho3+codopedZBYAglasses.Absorptionandemissionspectraaretestedtocharacterizethe2.7μmemissionpropertiesofEr3+/Tm3+andEr3+/Ho3+dopedZBYAglassesandareasonableenergytransfermechanismof2.7μmemissionbetweenEr3+andTm3+Ho3+)ionisproposed.CodopingofTm3+orHo3+significantlyreducesthelifetimeoftheEr3+:4I13/2levelduetotheenergytransferofEr3+:4I13/2→Tm3+:3F4orEr3+:4I13/2→Ho3+:5I7.Thus,the2.7μmemissionisstrengthenedandthe1.5μmemissionisdecreasedaccordinglyespeciallyintheEr3+/Tm3+sample.TheupconversioneffectsbetweentheEr3+/Tm3+andEr3+/Ho3+dopedZBYAglassesaredifferentattributetothedifferentenergytransferefficiencies.Bothofthetwocodopedsamplespossessnearlyequallargeemissioncrosssection(16.6×10-21cm-2)around2.7μm.TheresultsindicatethatthisEr3+/Tm3+orEr3+/Ho3+dopedZBYAglasshaspotentialapplicationsin2.7μmlaser.
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.
简介:Athree-dimensionalmodelofGaAs/A1GaAsquantumdoubleringsinthelateralstaticelectricfieldisinvestigatedtheoretically.Theeigenvalueproblemwiththeeffective-massapproximationissolvedbymeansofthefinite-elementmethod.Theenergylevelsandwavefunctionsofquantum-confinedelectronsandheavyholesareobtainedandshowanagreementwithourprevioustheoreticalandexperimentalstudies.ItisshownintheapproximationofneglectingtheCoulombattractionbetweentheelectronandheavyholethatarelativelylargeStarkshiftofexcitonemissionof4meVisattainablewithanappliedelectricfieldof0.7kV/cm.
简介:WecreateaGaNphotocathodebasedongradedAlxGa1-xNbufferlayerstoovercometheinfluenceofbuffer-emissionlayerinterfaceonthephotoemissionoftransmission-modeGaNphotocathodes.Agateshapedspectralresponsewitha260-nmstartingwavelengthanda375-nmcut-offwavelengthisobtained.Averagequantumefficiencyis15%andshortwavelengthresponsesarealmostequivalenttolongwavelengthones.Thefittedinterfacerecombinationvelocityis5×104cm/s,withnegligiblemagnitude,provingthatthedesignofthegradedbufferlayersisefficientinobtaininggoodinterfacequalitybetweenthebufferandtheemissionlayer.
简介:Anall-fiberopticallaserpulsemulti-passstretcherusingachirpedfiberBragggrating(CFBG)isdemonstrated.Pulsesfroma1053-nmmode-lockedfiberseedoscillatorarestretchedbymultiplepassingthroughachirpedfibergratingsetinafiberregenerativeamplifierstructure.Westretchthepulsefrom16psto1.855nsafterittransmitssevenloopsinthestretcher.Themainfactorsthataffectthestretchingresultsarediscussed.
简介:SiO_2thinfilmscontainingSi_(1-x)Ge_xquantumdots(QDs)arepreparedbyionimplantationandannealingtreatment.Thephotoluminescence(PL)andmicrostructuralpropertiesofthinfilmsareinvestigated.ThesamplesexhibitstrongPLinthewavelengthrangeof400—470nmandrelativelyweakPLpeaksat730and780nmatroomtemperature.Blueshiftisfoundforthe400-nmPLpeak,andtheintensityincreasesinitiallyandthendecreaseswiththeincreaseofGe-dopingdose.Weproposethatthe400—470nmPLbandoriginatesfrommultipleluminescencecenters,andthe730-and780-nmPLpeaksareascribedtotheSi=OandGeOluminescencecenters.
简介:卫星遥感、深空探测、电子对抗以及基础科学研究等领域的发展,促进着微波系统向着高频、宽带、大动态范围、广域覆盖等方向发展。传统的微波系统在微波信号的生成、分配、控制、处理等方面面临巨大挑战。微波光子学是研究微波和光波相互作用规律及应用的一门新兴学科,它利用光子学方法产生、分配、控制与处理宽带毫米波信号,被普遍认为是应对上述重大挑战的有效途径。重点阐述了微波光子技术的基本概念、发展历程及其应用前景;分析了微波光子技术面临的动态范围、转换效率、相位噪声等方面的挑战以及最新的研究成果;介绍了微波光子技术在干涉天线组阵、雷达模拟前端信号处理以及光钟方面的应用成果。