简介:Inthispaper,bothnonlinearsaturableabsorptionandtwo-photonabsorption(TPA)offew-layermolybdenumdiselenide(MoSe2)wereobservedat1.56μmwavelengthandfurtherappliedtomode-lockedultrafastfiberlaserforthefirsttimetoourknowledge.Few-layerMoSe2nanosheetswerepreparedbyliquid-phaseexfoliationmethodandcharacterizedbyxraydiffractometer,Ramanspectroscopy,andatomicforcemicroscopy.TheobtainedfewlayerMoSe2dispersionisfurthercompositedwithapolymermaterialforconvenientfabricationofMoSe2thinfilms.Then,weinvestigatedthenonlinearoptical(NLO)absorptionpropertyofthefew-layerMoSe2filmusingabalancedtwin-detectormeasurementtechnique.BoththesaturableabsorptionandTPAeffectsofthefew-layerMoSe2filmwerefoundbyincreasingtheinputopticalintensity.Thesaturableabsorptionshowsamodulationdepthof0.63%andalownonsaturablelossof3.5%,correspondingtotherelativemodulationdepthof18%.TheTPAeffectoccurredwhentheinputopticalintensityexceeds260MW∕cm2.Furthermore,weexperimentallyexploitthesaturableabsorptionoffew-layerMoSe2filmtomodelockanall-fibererbium-dopedfiberlaser.Stablesolitonmodelockingat1558nmcenterwavelengthisachievedwithpulsedurationof1.45ps.ItwasalsoobservedthattheTPAprocesssuppressesthemode-lockingoperationinthecaseofhigheropticalintensity.OurresultsindicatethatlayeredMoSe2,asanothertwo-dimensionalnanomaterial,canprovideexcellentNLOproperties(e.g.,saturableabsorptionandTPA)forpotentialapplicationsinultrashortpulsegenerationandopticallimiting.
简介:Liquid-phase-exfoliationtechnologywasutilizedtopreparelayeredMoS2,WS2,andMoSe2nanosheetsincyclohexylpyrrolidone.Thenonlinearopticalresponseofthesenanosheetsindispersionswasinvestigatedbyobservingspatialself-phasemodulation(SSPM)usinga488nmcontinuouswavelaserbeam.ThediffractionringpatternsofSSPMwerefoundtobedistortedalongtheverticaldirectionrightafterthelasertraversingthenanosheetdispersions.Thenonlinearrefractiveindexofthethreetransitionmetaldichalcogenidesdispersionsn2wasmeasuredtobe10-7cm2W-1,andthethird-ordernonlinearsusceptibilityχ(3)10-9esu.TherelativechangeofeffectivenonlinearrefractiveindexΔn2e∕n(2e)oftheMoS2,WS2,andMoSe2dispersionscanbemodulated0.012–0.240,0.029–0.154,and0.091–0.304,respectively,bychangingtheincidentintensities.Ourexperimentalresultsimplynovelpotentialapplicationoftwo-dimensionaltransitionmetaldichalcogenidesinnonlinearphasemodulationdevices.
简介:摘要:公路工程计量是工程建设一个重要的工作内容之一,是控制项目的工程投资与支出的非常关键的环节,也是约束着承包者履行合同义务的有效方法。鉴于公路工程计量工作重要性及如今所出现的工程计量问题,本文对如何做好工程计量的有关工作,提出了以下几点建议和措施。