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Control of plasmon dephasing time using stacked nanogap gold structures for strong near-field enhancement
摘要： The construction of metallic nanostructures with strong near-field enhancement is becoming increasingly significant for the practical use of plasmonic devices, such as plasmonic sensors and light-energy conversion systems. Importantly, the near-field enhancement effect depends on the plasmon dephasing time. Here, we propose a method for controlling plasmon dephasing time by utilizing plasmonic coupling for stronger near-field enhancement. Ordered arrays of stacked nanogap gold (Au) structures composed of a metal/insulator/metal nanostructure were fabricated by electron beam lithography and dry etching processes on a niobium-doped titanium dioxide substrate. The dark plasmon mode was excited by the near-field coupling between the upper and lower Au nanostructures separated by an alumina layer with a thickness of 15 nm. A strong near-field enhancement effect was induced by the localization of the electromagnetic field between the upper and lower Au nanostructures and the longer plasmon dephasing time based on the excitation of the dark plasmon mode. It is noteworthy that the dephasing time of the dark plasmon mode measured by time-resolved photoemission electron microscopy was extended 3-fold compared with that of the plasmon mode of the Au nanoblock, which can be controlled by the structural design of the stacked nanogap Au structures.
关键词： Dark plasmon mode,Plasmon dephasing,Near-field enhancement,Photoemission electron microscopy (PEEM),Surface plasmon resonance
更新于2025-09-23 15:23:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Tailoring Second-Harmonic Generation in Plasmonic Radial Trimers using Cylindrical Vector Beams
摘要： Collective effects in assemblies of plasmonic nanostructures are attracting widespread interest. Such effects are governed by the interactions among the constituents of the overall structure, providing an alternative path to modify plasmon resonances [1]. A particularly interesting collective effect in these structures is the so-called dark plasmon mode, which has a net zero dipole moment and cannot be accessed using plane waves or linearly polarized light under normal incidence. An emerging way to excite collective dark modes in such structures is through the use of cylindrical vector beams (CVB) that exhibit inhomogeneous states of polarization such as azimuthal or radial polarizations [2,3]. The use of CVBs to excite collective nonlinear optical effects such as second-harmonic generation (SHG) in oligomers has started only recently [4]. Here, we demonstrate a similar possibility by tailoring SHG in plasmonic radial trimers using CVBs.
关键词： dark plasmon mode,second-harmonic generation,cylindrical vector beams,plasmonic nanostructures
更新于2025-09-12 10:27:22