简介：Theimagesobtainedbyalargeopticaldetectionsystem(>500mm)arealwaysblurredbyatmosphericturbulence.Toaddressthisblurring,anadaptiveopticalsystemisurgentlyneeded.Here,a1.3mvehicle-basedadaptiveopticalsystem(VAOS),locatedontheNasmythfocus,isinvestigated.Atwo-gradetip/tiltsteeringmirrorisusedtoeliminatetrackingjitterandatmospherictippingerror.Pupilmatchingandcooperationbetweenthedeformablemirrorandthewavefrontsensorareadoptedtoachievehigh-orderaberrationmeasurementandcorrectionviaclosed-loopcorrectionandtoallowthetelescopetoobtainhigh-qualityimaging.Fordifferentseeingconditionsandsitelocations,theVAOSachievesthesensingoverthewavelengthrangefrom0.5μmto0.7μmusingaShack-Harmannwavefrontsensorandthecorrectionwitha97-unitdeformablemirrorforanimagingspectrumrangefrom0.7μmto0.9μm.Moreover,themaximumdetectioncapabilityofthesystemisgreaterthanavisualmagnitudeof5,andtheangularimagingresolutionisbetterthan0.3".

简介：A2×2cross/barpolymerelectro-optic(EO)routingswitchisproposed,whichiscomposedoftwopassivechannelwaveguidesandtwoactiveEOpolymermicroringswithbendingradiusofonly13.76μm.Detailedstructure,theoryandformulationareprovidedtocharacterizetheoutputpoweroftheswitch.Forobtainingfundamentalmodepropagation,smallbendinglossandphase-matchingbetweenchannelwaveguideandmicroringresonator(MRR)waveguide,thestructuralparametersareoptimizedunderthewavelengthof1550nm.Analysesandsimulationsonoutputpowerandoutputspectraindicatethataswitchingvoltageof5Visdesiredtorealizetheexchangebetweencrossstateandbarstate,thecrosstalkundercrossstateandthatunderbarstateareabout28.8dBand39.9dB,respectively,andtheinsertionlossesunderthesetwostatesareabout2.42dBand0.13dB,respectively.ComparedwithourfourEOswitchesreportedbefore,thisdevicepossessesultra-compactsizeof0.233mm×0.233mmaswellaslowcrosstalkandinsertionloss,andthereforeitcanserveasagoodcandidateforconstructinglarge-scaleopticalroutersorswitchingarraysinphotonicnetwork-on-chip(NoC).

简介：Timesynchronizationtechniques,especiallyonthepulsepersecond(PPS)temporalbasis,haveattractedgrowingresearchinterestsinrecentyears.Inthispaper,wehaveproposedandexperimentallydemonstratedahigh-precisiontwo-waytimetransfer(TWTT)systemtorealizelong-distancedisseminationof1PPSsignalgeneratedbyahydrogenmaser.Adense-wavelength-division-multiplexing(DWDM)systemandbi-directionalerbium-dopedfiberamplifiers(Bi-EDFAs)havealsobeenadoptedtosuppresstheimpactofRayleighbackscatteringandoptimizethesignaltonoiseratio(SNR)aswell.Wehavetheoreticallyanalyzedthesystematicdelayindetail.Theultimaterootmeansquare(RMS)variationoftimesynchronizationaccuracyissub-26psandthetimedeviationcanbereducedtoaslowas1.2psat100sand0.253psat12000s,respectively.

简介：Classicalnetworkreliabilityproblemsassumebothnetworksandcomponentshaveonlybinarystates,fullyworkingorfullyfailedstates.Butmanyactualnetworksaremulti-state,suchascommunicationnetworksandtransportationnetworks.Thenodesandarcsinthenetworksmaybeinintermediatestateswhicharenotfullyworkingeitherfullyfailed.Asimulationapproachforcomputingthetwo-terminalreliabilityofamulti-statenetworkisdescribed.Two-terminalreliabilityisdefinedastheprobabilitythatdunitsofdemandcanbesuppliedfromthesourcetosinknodesunderthetimethresholdT.Thecapacitiesofarcsmaybeinastochasticstatefollowinganydiscreteorcontinuousdistribution.Thetransmissiontimeofeacharcisalsonotafixednumberbutstochasticaccordingtoitscurrentcapacityanddemand.Tosolvethisproblem,acapacitatedstochasticcolouredPetrinetisproposedformodellingthesystembehaviour.Placesandtransitionsrespectivelystandforthenodesandarcsofanetwork.Capacitatedtransitionandself-modifiedtokencolourwithrouteinformationaredefinedtodescribethemulti-statenetwork.Bythesimulation,thetwo-terminalreliabilityandnodeimportancecanbeestimatedandtheoptimalroutewhosereliabilityishighestcanalsobegiven.Finally,twoexamplesofdifferentkindsofmultistatenetworksaregiven.

简介：:Twonovelpoly[(3-alkyhhiophene-2,5-diyl)-(benzylidenequinomethane-2,5-diyl)s]derivatives,poly[(3-butylthiophene-2,5-diyl)-(p-N,N-dimethylamino)benzylidenequinomethane-2,5-diyl)](PBTDMABQ)andpoly[-(3-octylthiophene2,5-diyl)-(p-N,N-dimethylamino)benzylidenequinomethane-2,5-diyl)](POTDMABQ),weresynthesized.Thebandgapsofthetwopolymersarecalculatedas1.75eVforPBTDMABQand1.69eVforPOTDMABQ,respectively.Thehomogenousfilmsofthetwopolymerswerepreparedandtheirthird-ordernonlinearopticalpropertieswerestudiedbythebackwarddegeneratefour-wavemixingat532nm.Byusingtherelativemeasurementtechnique,thethird-ordernonlinearopticalsusceptibilitiesofPBTDMABQandPOTDMABQarecalculatedas5.62×10^-9and1.22×10^-8ESU,respectively.Itisfoundthatsubstitutedalkygroupshavestrongeffectsonthebandgapandnonlinearopticalpropertiesofthetwopolymers.Therelativelybigthird-ordernonlinearopticalsusceptibilitiesandsmallbandgapofPOTDMABQresultedmainlyfromthelongeralkylwithstrongelectron-donatingabilitycanenhancethedelocationdegreeofconjugatedπelectronics.