简介:文中设计了一款64点基-4FFT处理器,用改进的CORDIC(MVR-CORDIC)处理单元代替常规FFT处理器中的复数乘法器,改进的CORDIC处理单元在保证SQNR性能下,仅用极少次数的移位加法运算即可完成一次复数乘法,缩减了完成一次基本蝶形运算的时间并减小了面积开销。该FFT处理器结构采用两块独立的RAM,并对中间数据作“乒-乓”式存储操作以节省数据存储时间,从而提高完成一次FFT运算的速度。所设计的FFT处理器通过FPGA进行验证,结果表明平均完成一次64点FFT运算仅需要不到1μs。
简介:Alow-thresholdefficienthigh-repetition-rateeye-safeopticalparametricoscillator(OPO)ispresented.TheOPOisbasedonanx-cutnon-criticallyphase-matched(NCPM)KTAintra-cavitypumpedbyanacousto-optically(A-O)Q-switchedNd:YVO4laser.At10kHz,thelowestthresholdof0.75Wandthesignalpowerof0.6Waregot,correspondingtothesinglepulseenergyof60μJandthepeakpowerof20kW.Tuningthefrequency,themaximumoutputpowerat1536nmis1.03Wat30kHzwithanoptical-to-opticalconversionefficiencyof12.26%.Thefluctuationoftheoutputpoweris2.1%during2hoperation.
简介:Adiode-pumpedacousto-optical(A-O)Q-switchedextra-cavityfrequency-doubledNd:YVO4/KTP(KTiOPO4)greenlaserformedwithasimpleplane-planecavityhasbeendemonstrated.Withtheincidentpumppowerof12.7W,A-OQ-switchedaverageoutputpowerat1064nmwas3.81Wwithadurationof25nsatarepetitionrateof20kHz,extra-cavityfrequencydoublingwithKTPasthenonlinearcrystalyieldedthemaximumoutputpowerof1.92Wat532nm,thecorrespondingopticalconversionefficiencyfrom1064nmto532nmlightis50.4%.Thecontinuous-wave(CW)laserpropertiesofdiodepumpedNd:YVO4crystaloperatingat1064nmhavebeenstudied.Withtheincidentpumppowerof25W,themaximumCWoutputpowerof13.81Wwasobtainedwiththecorrespondingopticalconversionefficiencyof55.24%.
简介:Additivesandiodine(I2)areusedtomodifythebinaryroomtemperatureionicliquid(RTIL)electrolytetoenhancethephotovoltaicperformanceofdye-sensitizedsolarcells(DSSCs).Theshort-circuitcurrentdensity(JSC)of17.89mA/cm2,opencircuitvoltage(VOC)of0.71Vandfillfactor(FF)of0.50areachievedintheoptimaldevice.Anaveragephotoelectricconversionefficiency(PCE)of6.35%isachievedbyoptimization,whichisovertwotimeslargerthanthatoftheparentdevicebeforeoptimization(2.06%),whilethemaximumPCEcanreachupto6.63%.
简介:Dy3+/Eu3+共掺杂的立方格子NaYF4单晶在~Φ×1厘米大小为10厘米高质量的改进布里奇曼法用氟化钾(KF)作为助熔剂生长。射线衍射(X射线衍射),吸收光谱,激发光谱和发射光谱测量的晶体的相位和发光性能的晶体。分析了激发波长和Dy3+和Eu3+离子浓度对发光特性的影响。NaYF4单晶的掺杂摩尔浓度的1.205%和0.366%的Eu3+,Dy3+具有优良的白色发光的色度坐标x=0.321,y=0.332。这表明Dy3+/Eu3+共掺的立方格子NaYF4单晶可以潜在的发光材料的紫外(UV)光激发的白光发光二极管(LED)。
简介:srzn2(PO4)2:在大气中的高温固相反应合成Sm3+荧光粉。srzn2(PO4)2:Sm3+荧光粉是通过紫外光有效激发(UV)和蓝色光,和发射峰被分配到2-6h54G5//2过渡(563nm),2-6h74G5//2(597nm和605nm)和2-6h94G5//2(644nm和653nm)。对srzn2发射强度(PO4)2:Sm3+的Sm3+浓度的影响,其浓度猝灭效应srzn2(PO4)2:钐也观察到。当掺杂离子(=Li,Na和K)离子的发光强度,srzn2(PO4)2:Sm3+可以明显增强。在国际照明委员会(CIE)的srzn2色坐标(PO4)2:Sm3+定位在橙红色的区域。结果表明,该荧光粉具有潜在的应用在白光发光二极管(LED)。
简介:Lanthanidehasattractedmuchattentioninthefieldofopticalcommunicationsinrecentyears.SomepropertyanalysesonopticalwaveguideofNd-dopedcrystalNdxY1-xAl3(BO3)4andNd:MgO:LiNbO3aremadeinthispaper,followedbyintroductionofthemethodsofexperimentationandtheoreticalcalculationfortheplanaropticalwaveguides.Therefractiveindexprofilesoftheopticalwaveguidesareanalyzed.Theaboveworkoffersusefulinformationforstudyonnewtypematerialsforopticalcommunications.