简介：Wedevelopahybridoptofluidicmicrocavitybyplacingamicrospherewithadiameterrangingfrom1to4μminliquid-filledplano-planoFabry–Perot(FP)cavities,whichcanprovideanextremelyloweffectivemodevolumedownto0.3–5.1μm^3whilemaintainingahighQ-factorupto1×10^4–5×10^4andafinesseof~2000.Comparedtothepureplano-planoFPcavitiesthatareknowntosufferfromthelackofmodeconfinement,diffraction,andgeometricalwalk-offlossesaswellasbeinghighlysusceptibletomirrormisalignment,ourmicrosphere-integratedFP(MIFP)cavitiesshowstrongopticalconfinementinthelateraldirectionwithatightmoderadiusofonly0.4–0.9μmandhightolerancetomirrormisalignmentaslargeas2°.Withthemicrosphereservingasawaveguide,theMIFPisadvantageousoverafiber-sandwichedFPcavityduetotheopen-cavitydesignforanalytes/liquidstointeractstronglywiththeresonantmode,theeaseofassembly,andthepossibilitytoreplacethemicrosphere.Inthiswork,themaincharacteristicsoftheMIFP,includingQ-factor,finesse,effectivemoderadiusandvolume,andtheirdependenceonthesurroundingmedium’srefractiveindex,mirrorspacing,microspherepositioninsidetheFPcavity,andmirrormisalignment,aresystematicallyinvestigatedusingafinite-elementmethod.Then,byinsertingdye-dopedpolystyrenemicrospheresofvarioussizesintotheFPcavityfilledwithwater,weexperimentallyrealizesingle-modeMIFPoptofluidiclasersthathavealasingthresholdaslowasafewmicrojoulespersquaremillimeterandalasingspotradiusofonly~0.5μm.OurresultssuggestthattheMIFPcavitiesprovideapromisingtechnologyplatformfornovelphotonicdevicesandbiological/chemicaldetectionwithultra-smalldetectionvolumes.

简介：WeproposeanddemonstrateawidelytunablepassivelyQ-switchedHo^3+∕Pr^3+-codopedZrF4-BaF2-LaF3-AlF3-NaFfiberlaseroperatinginthe2.8μmmid-infrared(MIR)wavebandbasedonasingle-walledcarbonnanotube(SWCNT)saturableabsorber(SA).TheSWCNTshavediametersrangingfrom1.4to1.7nm.ThemodulationdepthandsaturationintensityoftheSWCNTSAmeasuredat2850nmare16.5%and1.66MW∕cm^2,respectively.StableQ-switchedpulseswiththeshortestpulsedurationof1.46μsandthemaximumpulseenergyof0.43μJareachievedatalaunchedpumppowerof445.6mW.ThecombineduseofabroadbandSWCNTSAandaplaneruledgratingensuresabroadcontinuouslytuningrangeof55.0nmfrom2837.6to2892.6nm.Theoutputpowers,emissionspectra,repetitionrates,andpulsedurationsatdifferenttuningwavelengthsarealsocharacterizedandanalyzed.OurresultsindicatethatSWCNTscanbeexcellentbroadbandSAsinthe3μmMIRregion.Totheauthor’sknowledge,thisisthefirstdemonstrationofawidelytunablecarbon-nanotubeenabledpassivelyQ-switchedfiberlaseroperatinginthe2.8μmMIRwaveband.

简介：Photonics-basedradarwithaphotonicde-chirpreceiverhastheadvantagesofbroadbandoperationandreal-timesignalprocessing,butitsuffersfrominterferencefromimagefrequenciesandotherundesiredfrequency-mixingcomponents,duetosingle-channelreal-valuedphotonicfrequencymixing.Inthispaper,weproposeaphotonicsbasedradarwithaphotonicfrequency-doublingtransmitterandabalancedin-phaseandquadrature(I/Q)de-chirpreceiver.Thisradartransmitsbroadbandlinearlyfrequency-modulatedsignalsgeneratedbyphotonicfrequencydoublingandperformsI/Qde-chirpingoftheradarechoesbasedonabalancedphotonicI/Qfrequencymixer,whichisrealizedbyapplyinga90°opticalhybridfollowedbybalancedphotodetectors.Theproposedradarhasahighrangeresolutionbecauseofthelargeoperationbandwidthandachievesinterference-freedetectionbysuppressingtheimagefrequenciesandotherundesiredfrequency-mixingcomponents.Intheexperiment,aphotonics-basedK-bandradarwithabandwidthof8GHzisdemonstrated.ThebalancedI/Qde-chirpingreceiverachievesanimage-rejectionratioofover30dBandsuccessfullyeliminatestheinterferenceduetothebasebandenvelopeandthefrequencymixingbetweenradarechoesofdifferenttargets.Inaddition,thedesireddechirpedsignalpowerisalsoenhancedwithbalanceddetection.Basedontheestablishedphotonics-basedradar,inversesyntheticapertureradarimagingisalsoimplemented,throughwhichtheadvantagesoftheproposedradarareverified.

简介：WereportQ-switchedandmode-lockederbium-dopedall-fiberlasersusingternaryReS2(1-x)Se2xassaturableabsorbers(SAs).ThemodulationdepthandsaturableintensityofthefilmSAare1.8%and0.046MW∕cm2.InQ-switchedmechanismoutput,thepulsewascenteredat1531.1nmwithmaximumpulseenergyandminimumpulsewidthof28.29nJand1.07μs,respectively.Inmode-lockedoperation,thepulsewascenteredat1561.15nmwithpulsewidthof888fs,repetitionrateof2.95MHz,andmaximumpulseenergyof0.275nJ.Tothebestofourknowledge,thisisthefirstreportonthemode-lockedEr3+-dopedfiberlaserusingternarytransitionmetaldichalcogenides.Thisworksuggestsprospective2D-materialSAscanbewidelyusedinversatilefieldsduetotheirattractiveoptoelectronicandtunableenergybandgapproperties.