Plasmonic nanoparticle on mirror antennas with sub-10 nm gaps have shown the great potential in nanophotonic applications because they offer tightly confined electric field in the gap and resultant large Purcell factors. However, in a nanosphere on mirror (NSoM) structure being studied experimentally, the degree of freedom of the antennas in terms of spectral and polarization control is limited. In this work, we report spectral shaping and polarization control of Purcell-enhanced fluorescence by the gap plasmon modes of an anisotropic gold (Au) nanorod on a mirror (NRoM) antenna. Systematic numerical calculations demonstrate the richer resonance behaviors of a NRoM antenna than a NSoM antenna due to the hybridization of the bright and dark modes. We fabricate a NRoM antenna by placing a Au NR on an ultraflat Au film via a mono-, double-, or quadruple-layers of light emitting quantum dots (QDs) (3 nm in diameter). The scattering spectra of single NRoM antennas coincide very well with those of the numerical simulations. We demonstrate large enhancement (>900-fold) and strong shaping of the luminescence from QDs in the gap due to the coupling with the hybridized mode of a NRoM antenna. We also show that the polarization property of the emission is controlled by that of the mode coupled.

中文翻译：

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镜面纳米天线上的金纳米棒的杂化等离子间隙模式用于光谱定制的荧光增强。

具有小于10 nm间隙的镜面天线上的等离子纳米粒子在纳米光子应用中显示出巨大的潜力，因为它们在间隙中提供了紧密受限的电场并产生了较大的赛尔（Purcell）因子。但是，在实验研究的纳米球镜结构（NSoM）中，天线在频谱和极化控制方面的自由度受到限制。在这项工作中，我们报告了通过镜面（NRoM）天线上的各向异性金（Au）纳米棒的间隙等离子体激元模式对赛尔增强荧光的光谱整形和偏振控制。系统数值计算表明，由于亮模式和暗模式的混合，NRoM天线比NSoM天线具有更丰富的谐振行为。我们通过将Au Au NR通过单，双，或四层发光量子点（QD）（直径3 nm）。单个NRoM天线的散射光谱与数值模拟的光谱非常吻合。由于与NRoM天线的混合模式耦合，我们证明了间隙中来自QD的发光的大幅度增强（> 900倍）和强整形。我们还表明，发射的偏振特性受耦合模式的偏振特性控制。