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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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Plasmonics of regular shape particles, a simple group theory approach
摘要： A simple hand calculation method based on group theory is proposed to predict the near field maps of finite metallic nanoparticles (MNP) of canonical geometries: prism, cube, hexagon, disk, sphere, etc. corresponding to low order localized surface plasmon resonance excitations. In this article, we report the principles of the group theory approach and demonstrate, through several examples, the general character of the group theory method which can be applied to describe the plasmonic response of particles of finite or infinite symmetry point groups. Experimental validation is achieved by collection of high-resolution subwavelength near-field maps by photoemission electron microscopy (PEEM) on a representative set of Au colloidal particles exhibiting either finite (hexagon) or infinite (disk, sphere) symmetry point groups.
关键词： hexagon,disk,photoemission electron microscopy (PEEM),group theory,sphere,surface plasmon resonance
更新于2025-09-23 15:19:57