简介：Transformationacousticsareconcentratedforthepurposeofdesigningnovelacousticdevicestotailoracousticwavestoachievedesirablecharacteristics.However,thesedevicesrequirefluidorfluid-likematerialswithananisotropicdensitythatgenerallydoesnotexistinnature.Therefore,weintroducepentamodemetamaterialsintoanalternatingmultilayerisotropicmediummodeltobuildfluid-likemetamaterialswithananisotropicdensity.A2Dacousticbendingbasedontransformationacousticsisestablishedandinvestigatedtoverifyourmethod.Thisideaprovidesamethodtodesignbroadbandandphysicallyrealizableacousticmetamaterialswithananisotropicdensityandismeaningfulforthedesignofacousticmetamaterials.

简介：Interestinthenonlinearpropertiesofmulti-modeopticalwaveguideshasseenarecentresurgenceonaccountofthelargedimensionalityaffordedbytheplatform.Thelargevolumeofmodesinthesewaveguidesprovidesanewspatialdegreeoffreedomforphasematchingnonlinearopticalprocesses.However,thisspatialdimensionisquantized,whichnarrowstheconversionbandwidthsofintermodalprocessesandconstrainsspectralandtemporaltailoringofthelight.Hereweshowthatbyengineeringtherelativegroupvelocitywithinthespatialdimension,wecantailorthephase-matchingbandwidthofintermodalparametricnonlinearities.Wedemonstrategroup-velocity-tailoredparametricnonlinearmixingbetweenhigher-ordermodesinamulti-modefiberwithgainbandwidthsthataremorethananorderofmagnitudelargerthanthatpreviouslythoughtpossibleforintermodalfour-wavemixing.Asevidenceofthetechnologicalutilityofthismethodology,weseedthisprocesstogeneratethefirsthigh-peak-powerwavelength-tunableall-fiberquasi-CWlaserintheTi:sapphirewavelengthregime.Moregenerally,withthecombinationofintermodalinteractions,whichdramaticallyexpandthephase-matchingdegreesoffreedomfornonlinearoptics,andintermodalgroup-velocityengineering,whichenablestailoringofthebandwidthofsuchinteractions,weshowcaseaplatformfornonlinearopticsthatcanbebroadbandwhilebeingwavelengthagnostic.

简介：Polarizationmanipulationisasignificantissueforartificialmodulationoftheelectromagnetic(EM)wave,butgeneralmechanismsallsuffertherestrictionofinherentsymmetricpropertiesbetweenoppositehandedness.Herein,astrategytoindependentlyandarbitrarilymanipulatetheEMwavewithorthogonalcircularpolarizationsbasedonametasurfaceisproposed,whicheffectuallybreaksthroughtraditionalsymmetricalcharacteristicsbetweenorthogonalhandedness.Bysynthesizingthepropagationphaseandgeometricphase,theappropriateJonesmatrixiscalculatedtoobtainindependentwavefrontmanipulationofEMwaveswithoppositecircularpolarizations.Twotransmissiveultra-thinmeta-deflectorsareproposedtodemonstratetheasymmetricalrefractionoftransmittedcircularlypolarizedwavesinthemicrowaveregion.Simulatedtransmittedphasefrontandmeasuredfar-fieldintensitydistributionsareinexcellentagreement,indicatingthatthetransmittedwavewithdifferentpolarizationscanberefractedintoarbitraryandindependentdirectionswithinawidefrequencyband(relativebandwidthof25%).TheresultspresentedinthispaperprovidemorefreedomforthemanipulationofEMwaves,andmotivatetherealizationsofvariouspolarization-independentpropertiesforallfrequencyspectra.

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.