简介：Afullycoherentfreeelectronlaser(FEL)seededwithahigher-orderharmonic(HH)pulsefromhigh-orderharmonicgeneration(HHG)issuccessfullyoperatedforasufficientlyprolongedtimeinpilotuserexperimentsbyusingatimingdriftfeedback.ForHHG-seededFELs,theseedinglaserpulseshavetobesynchronizedwithelectronbunches.DespiteseededFELsbeingnon-chaoticlightsourcesinprinciple,externallaser-seededFELsareoftenunstableinpracticebecauseofatimingjitterandadriftbetweentheseedinglaserpulsesandtheacceleratedelectronbunches.Accordingly,weconstructedarelativearrival-timingmonitorbasedonnon-invasiveelectro-opticsampling(EOS).TheEOSmonitormadeuninterruptedshot-to-shotmonitoringpossibleevenduringtheseededFELoperation.TheEOSsystemwasthenusedforarrival-timingfeedbackwithanadjustabilityof100fsforcontinualoperationoftheHHG-seededFEL.UsingtheEOS-basedbeamdriftcontrollingsystem,theHHG-seededFELwasoperatedoverhalfadaywithaneffectivehitrateof20%–30%.Theoutputpulseenergywas20μJatthe61.2nmwavelength.TowardsseededFELsinthewaterwindowregion,weinvestigatedourupgradeplantoseedhigh-powerFELswithHHphotonenergyof30–100eVandlaseatshorterwavelengthsofupto2nmthroughhigh-gainharmonicgeneration(HGHG)attheenergy-upgradedSPring-8CompactSASESource(SCSS)accelerator.WestudiedabenefitaswellasthefeasibilityofthenextHHG-seededFELmachinewithsingle-stageHGHGwithtunabilityofalasingwavelength.

简介：Tuningthecoloroutputofrare-earthiondopedluminescentnanomaterialshasimportantscientificsignificanceforfurtherextendingapplicationsincolordisplays,lasersources,optoelectronicdevices,andbiolabeling.Inpreviousstudies,pre-designedphasemodulationofthefemtosecondlaserfieldhasbeenproventobeeffectiveintuningtheluminescenceofdopedrare-earthions.Owingtothecomplexlight–matterinteractionintheactualexperiment,thedynamicrangeandoptimalefficiencyforcolortuningcannotbedeterminedwiththepre-designedphasemodulation.Thisarticlesharesthedevelopmentofanadaptivefemtosecondpulseshapingmethodbasedonageneticalgorithm,anditsusetomanipulatethegreenandredluminescencetuninginanEr3+-dopedglassceramicunder800-nmfemtosecondlaserfieldexcitationforthefirsttime.ExperimentalresultsshowthattheintensityratioofthegreenandredUCluminescenceofthedopedEr3+ionscanbeeitherincreasedordecreasedconvenientlybythephase-shapedfemtosecondlaserfieldwithanoptimalfeedbackcontrol.Thephysicalcontrolmechanismsforthecolortuningarealsoexplainedindetail.Thisarticledemonstratesthepotentialapplicationsoftheadaptivefemtosecondpulseshapingtechniqueincontrollingthecoloroutputofdopedrare-earthions.

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