Zhang Feifei, Martin Jérôme, Murai Shunsuke, Adam Pierre-Michel, Plain Jérôme, Tanaka Katsuhisa
Opt Express. 2021 May 10;29(10):14799-14814. doi: 10.1364/OE.425136.
A single metallic nanodisk is the simplest plasmonic nanostructure, but it is robust enough to generate a Fano resonance in the forward and backward scattering spectra by the increment of nanodisk height in the symmetric and asymmetric dielectric environment. Thanks to the phase retardation effect, the non-uniform distribution of electric field along the height of aluminum (Al) nanodisk generates the out-of-plane higher-order modes, which interfere with the dipolar mode and subsequently result in the Fano-lineshape scattering spectra. Meanwhile, the symmetry-breaking effect by the dielectric substrate and the increment of refractive index of the symmetric dielectric environment further accelerate the phase retardation effect and contribute to the appearance of out-of-plane modes. The experimental results on the periodic Al nanodisk arrays with different heights confirm the retardation-induced higher modes in the asymmetric and symmetric environment. The appearance of higher modes and blueshifted main dips in the transmission spectra prove the dominant role of out-of-plane higher modes on the plasmonic resonances of the taller Al nanodisk.
单个金属纳米盘是最简单的等离子体纳米结构，但在对称和非对称介电环境中，通过增加纳米盘高度，它足以在向前和向后散射光谱中产生法诺共振。由于相位延迟效应，沿铝（Al）纳米盘高度方向的电场非均匀分布会产生面外高阶模式，这些模式与偶极模式相互干涉，进而导致法诺线型散射光谱。同时，介电基底的对称破缺效应以及对称介电环境中折射率的增加进一步加速了相位延迟效应，并促使面外模式的出现。关于不同高度的周期性Al纳米盘阵列的实验结果证实了在非对称和对称环境中由延迟引起的高阶模式。传输光谱中高阶模式的出现和主凹陷的蓝移证明了面外高阶模式在较高Al纳米盘的等离子体共振中起主导作用。
