简介:Thestructureoftheopticalwaveguideof2-bitelectroopticA/Dconverterwithproton-exchangemicroprismsisoptimizedbythefinite-differencebeampropagationmethod(FD-BPM).Theelectrodeparametersoftheconverterareoptimizedbyconformalmapping.Theoptimalparametersareahalf-wavevoltageofVπ=4.5VandabandwidthofΔf=1.4GHz.Anormalizedtransmittedpowerof69.75%isobtainedbyFD-BMPandtheoutputwaveguidegapis300μm.
简介:A2D-directionofarrivalestimation(DOAE)formultiinputandmulti-output(MIMO)radarusingimprovedmultipletemporal-spatialsubspacesinestimatingsignalparametersviarotationalinvariancetechniquesmethod(TS-ESPRIT)isintroduced.InordertorealizetheimprovedTS-ESPRIT,theproposedalgorithmdividestheplanararrayintomultipleuniformsub-planararrayswithcommonreferencepointtogetaunifiedphaseshiftsmeasurementpointforallsub-arrays.TheTS-ESPRITisappliedtoeachsub-arrayseparately,andinthesametimewiththeotherstorealizetheparallellytemporalandspatialprocessing,sothatitreducesthenon-linearityeffectofmodelanddecreasesthecomputationaltime.Then,thetimedifferenceofarrival(TDOA)techniqueisappliedtocombinethemultiplesub-arraysinordertoformtheimprovedTS-ESPRIT.Itisfoundthattheproposedmethodachieveshighaccuracyatalowsignaltonoiseratio(SNR)withlowcomputationalcomplexity,leadingtoenhancementoftheestimatorsperformance.
简介:Anultra-highspeed1:2demultiplexerforopticalfibercommunicationsystemsisdesignedutilizingtheIHP0.25μmSiGeBiCMOStechnology.Thelatchofthedemultiplexercorecircuitisresearched.Basedonthecurrentmeasurementcondition,ahigh-gainandwide-bandwidthclockbufferisdesignedtodrivelargeload.Transmissionlinetheoryforultra-highspeedcircuitsisusedtodesignmatchingnetworktosolvethematchingproblemamongtheinput,outputandinternalsignals.Thetransientanalysisshowsthatthisdemultiplexercandemultiplexone100Gb/sinputintotwo50Gb/soutputs.Thechipareaofitis0.7mm×0.47mm,theinputandoutputdataarebothat400mVP-PPCMLstandardvoltagelevel,andthepowerconsumptionoftheICis900mWatthepowersupplyof-4V.
简介:Thispaperpresentsanewarraystructureforestimatingtwo-dimensional(2-D)direction-of-arrivals(DOAs).ThestructureiscalledY-shapedarray,whichhas10%betteraccuracypotentialthanthenewly-developedL-shapedarray.Agreatmeritisitsabilitytoestimate2-DDOAswhicheverdirectionsthearrivingsignalscomefrom,comparedwithL-shapedarraywhoseperformancedependsonDOAs.Simulationresultsaregiventodemonstratetheperformanceofthenewarray.
简介:Aterahertz(THz)polarizerandswitchstructureisproposedbasedonthephasetransitionofvanadiumdioxide(VO2).WhenVO2isintheinsulationphase,theresonancefrequenciesoftheproposedstructureare1.49THzand1.22THzforthex-andy-polarization,respectively.ItcanperformasaTHzpolarizerwithextinctionratiosof52.5dBand17dBforthey-andx-polarization,respectively;WhenVO2transformsintometallicphase,theresonancefrequencyforx-polarizationwaveshiftsfrom1.49THzto1.22THz,whilethatremainsstillforthey-polarizationcomponent.Itmeansthatthestructurecanworkasapolarization-dependentTHzswitchwithahighextinctionratioof32dB.
简介:AninitialstructuredesignofMMI1×8opticalpowersplittersisreported.ThewaveguidematerialisSi-basedSiO2Ge-dopedanddepositedbyPECVDmethod.Embeddedstripstructureisimpliedinthesectiondesign.ByusingBPM-CAD,afavorableresultisobtainedthatthisdevicehasasounduniformityandfairlylowloss.Meanwhile,simulationsofdesignswithcertainchangedparametersisalsoimplementedforabetterdesignconfiguration.
简介:UnipolarresistiveswitchingbehaviorsoftheZnOandAl2O3/ZnOfilmsfabricatedonflexiblesubstratesbypulselaserdepositionwerestudiedinthispaper.Thefilmsweredepositedatroomtemperaturewithoutpost-annealingtreatmentduringtheprocess.XraydiffractionresultsindicatedthatZnOfilmhasadominantpeakat(002).ScanningelectronmicroscopyobservationshowedacolumnargrainstructureoftheZnOfilmtothesubstrate.ThebilayerdeviceofAl2O3/ZnOfilmshadstableresistiveswitchingbehaviorswithagoodenduranceperformanceofmorethan200cycles,highresistiveswitchingratioofover103atareadvoltageof0.1V,whichisbetterthanthatofthesingleoxidelayerdeviceofZnOfilm.Apossibleresistiveswitchingfilamentarymodewasdemonstratedinthispaper.TheconductionmechanismsofhighandlowresistancestatescanbeexplainedbyspacechargelimitedconductionandOhmic’sbehaviors.Theenduranceofthebilayer(BL)devicewasnotdegradeduponbendingcycles,whichindicatesthepotentialoftheflexibleresistiveswitchingrandomaccessmemoryapplications.
简介:Thesilicon-on-insulator(SOI)1×2Y-junctionopticalwaveguideswitchhasbeenproposedandfabricated,whichisbasedonthelargecross-sectionsingle-moderibwaveguidecondition,thewaveguide-vanishingeffectandthefree-carrierplasmadispersioneffect.Intheswitch,theSOItechniqueutilizersiliconandsilicondioxidethermalbondingandback-polishing.Theinsertionlossandextinctionratioofthedevicearemeasuredtobelessthan4.78dBand20.8dBrespectivelyatawavelengthof1.3μmandaninjectioncurrentof45mA.Responsetimeisabout160ns.
简介:Themixedl1/H2optimizationproblemforMIMO(multipleinput-multipleoutput)discrete-timesystemsisconsidered.Thisproblemisformulatedasminimizingthel1-normofaclosed-looptransfermatrixwhilemaintainingtheH2-normofanotherclosed-looptransfermatrixatprescribedlevel.ThecontinuitypropertyoftheoptimalvalueinrespecttochangesintheH2-normconstraintisstudied.Theexistenceoftheoptimalsolutionsofmixedll/H2problemisproved.Becausethesolutionofthemixedl1/H2problemisbasedonthescaled-Qmethod,itavoidsthezerointerpolationdifficulties.Theconvergentupperandlowerboundscanbeobtainedbysolvingasequenceoffinitedimensionalnonlinearprogrammingforwhichmanyefficientnumericaloptimizationalgorithmsexist.
简介:Anultrahighvacuumchemicalvapordeposition(UHV/CVD)systemisintroduced.SiGealloysandSiGe/Simultiplequantumwells(MQWs)havebeengrownbycold-wallUHV/CVDusingdisilane(Si2H6)andgermane(GeH4)asthereactantgasesonSi(100)substrates.ThegrowthrateandGecontentsinSiGealloysarestudiedatdifferenttemperatureanddifferentgasflow.ThegrowthrateofSiGealloyisdecreasedwiththeincreaseofGeH4flowathightemperature.X-raydiffractionmeasurementshowsthatSiGe/SiMQWshavegoodcrystallinity,sharpinterfaceanduniformity.Nodislocationisfoundintheobservationoftransmissionelectronmicroscopy(TEM)ofSiGe/SiMQWs.TheaveragedeviationofthethicknessandthefractionofGeinsingleSiGealloysampleare3.31%and2.01%,respectively.
简介:WefabricatepolycrystallineCu(In,Ga)Se2(CIGS)filmsolarcellsonpolyimide(PI)substrateattemperatureof450°Cwithsingle-stageprocess,andobtainapoorcrystallizationofCIGSfilmswithseveralsecondaryphasesinit.Forimprovingitfurther,thetwo-stageprocessisadoptedinsteadofthesingle-stageone.AnextraCu-richCIGSlayerwiththethicknessfrom100nmto200nmisgrownonthesubstrate,andthenanotherCu-poorCIGSfilmwiththicknessof1.5-2.0μmisdepositedonit.Withthemodificationoftheevaporationprocess,thegrainsizeofabsorberlayerisincreased,andtheadditionalsecondaryphasesalmostdisappear.Accordingly,theoveralldeviceperformanceisimproved,andtheconversionefficiencyisenhancedbyabout20%.