| By constructing metal micro-nano structure,the unique properties of surface plasmon polariton resonances are used to enhance the emission efficiency by increasing the localized state density around nanostructure.Modifying spontaneous emission efficiency of fluorescence spatially and spectrally is of great interest in the study of nanophotonics.Metasurface,composing of subwavelength "meta-atoms" in periodic arrangement with ultra-thin film,can be used to modify phase,amplitude and polarization of electromagnetic wave,also can provide new choice to design integrated optical components with various functions.Therefore,metasurface has been widely concerned because of its ability to reduce intrinsic losses of metal and recent advances in nanofabrication techniques to produce complex nanostructures.However,little work has been done about manipulating fluorescence emission based on the diverse electromagnetic properties of metasurface,in order to realize the active device design.The ability to reduce intrinsic losses of metal,and the highly efficient capability to confine light within nanoscale volume with the help of plasmon resonance of metal nanostructure,have significant advantages in terms of fluorescence mediation.This dissertation considers to use MPP mode to mediate fluorescence emission,and comes up with a metal-dielectric-metal(MDM)metasurface combined with multiple electromagnetic modes.The modes properties,field enhanced properties and fluorescence emission manipulation properties are studied.Our research will provide new perspectives and perspectives for specific applications,including nanoscale light source and fluorescence spectroscopy.This dissertation presents the research works and conclusions,as following:1.We design and fabricate a metal-dielectric-metal(MDM)fishnet metasurface with multiple types of resonance modes that occur in the visible spectral range.The parametric dependences of the multiple resonant wavelengths are all carefully analyzed by use of a reasonable inductor-capacitor(LC)circuit modes and the finite-difference time-domain(FDTD)simulations,experimentally and numerically.Based on these studies,a polarization-dependent spectral tunable device is designed.Our research is useful for designing of color filter and sensors.2.Based on the LSP and MPP modes' excellent ability to confine light within a nanoscale volume in the structure,we design and fabricate an active MDM fishnet metasurface with double enhancement on both the fluorescence excitation and emission efficiency.The resonance wavelengths of these two modes are matched to the fluorescence molecules' absorption and emission peaks,respectively.Moreover,the polarization-dependent electric fields of these two modes are overlapped.This device can realize the polarization-dependent spatial selective excitation and enhancement of fluorescence emission,as well as modify of fluorescence emission.The adjusted fluorescence exhibits polarized and directional emission.The design of this structure provides meaningful guidance for realizing wavelength and polarization tunable light emitting devices in the visible range.3.Based on the above research,taking account of the fluorescence emission absorption and interference of modes from the metal film,we design and fabricate an active MDM particle metasurface with higher fluorescence emission efficiency,more controllable modes and wider range of selectable wavelength.Based on the metasurface polarizability tensor calculation and FDTD simulation,we theoretically design a dual modes homogenous and heterogeneous particle metasurface to realize double enhanced fluorescence emission.Moreover,we design and fabricate a dual modes MDM particle metasurface with LSP and MPP mode,then study the mode property together with the fluorescence emission property by varying the structure parameters,and find that the controllable range of emission wavelength is obviously larger than the MDM fishnet metasurface when the periodic mode effect is excluded.Highlights in this dissertation are as following:1.We use both the MPP mode in MDM fishnet metasurface to mediate the fluorescence emission.An LC circuit model is constructed to describe the MPP mode.The theoretical prediction fit the experimental data very well,with an average relative difference of less than 1.5%.This model is concise,resonable and effective,help to understand the properties of MPP mode in MDM fishnet metasurface from new aspect.2.We systematically investigate the tunable property of multiple types of resonance modes that occur in a MDM fishnet metasurface,including MPP,LSP and SPP-BW.The parametric dependences of the multiple resonant wavelengths are all carefully analyzed,indicating that the MPP mode is more easily tunable than the other modes.Based on these studies,a polarization-dependent spectral tunable device is designed.3.Using the property that the LSP and MPP mode supported in MDM metasurface can confine light field in nanogap layer,we design and fabricate an active MDM fishnet and particle metasurface with double enhancement on both the fluorescence excitation and emission efficiency.This device can realize the polarization-dependent spatial selective excitation in the visible range,and MPP mode dependent fluorescence emission spectrum,polarization and angle modification. |
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