Hybridized surface lattice modes in intercalated 3-disk plasmonic crystals for high figure-of-merit plasmonic sensing

Engineering the spectral lineshape of plasmonic modes by various electromagnetic couplings and mode interferences enables significant improvements for plasmonic sensing. However, bulk and surface sensitivities remain constrained by a trade-off arising from their respective dependence on the interaction volume and decay length of the plasmonic mode, making higher bulk sensitivity realized at the expense of reduced surface sensitivity. We propose a new approach to overcome this trade-off by combining near-field and far-field coupling in an intercalated 3-disk plasmonic crystal, where similar to 10x higher figure of merit (FoM) and similar to 2x higher surface sensitivity can be achieved, in comparison with those achievable by localized surface plasmons. A plasmonic mode with a Q-factor up to similar to 110 is demonstrated based on gold 3-disk arrays in the visible spectrum, with a bulk FoM of similar to 24 and a surface sensitivity prefactor of similar to 13.56. The design and fabrication simplicity of the 3-disk structure highlight its potential for a robust plasmonic sensing platform with a high figure of merit.

Automated summary

Engineering the spectral lineshape of plasmonic modes through various electromagnetic couplings and mode interferences can significantly improve plasmonic sensing. A new approach is proposed to overcome the trade-off between bulk and surface sensitivities by combining near-field and far-field coupling in an intercalated 3-disk plasmonic crystal, achieving higher figure of merit and surface sensitivity. The design simplicity and high figure of merit highlight the potential of the 3-disk structure for a robust plasmonic sensing platform.