Experimentally demonstrating plasmonic lattice mode in periodic Ag nanoparticle arrays on quartz trapezoidal pillars

Abstract

A plasmonic lattice mode (PLM) is demonstrated in the periodic Ag nanoparticle arrays, which are fabricated by thermal evaporation and focused-ion beam. In the arrays, each Ag nanoparticle is located on the top of a quartz trapezoidal pillar, which sits on a quartz substrate. Higher quartz trapezoidal pillars can make the transmittance of the structure vary rapidly from the maximum to the minimum in a narrow wavelength band due to the coupling between localized surface plasmonic resonance of Ag nanoparticles and the wavelength-dependent diffraction, while the phenomenon cannot be observed in the structure with lower pillars. FDTD simulation not only gives results which are similar to the experimental ones, but also shows that, when the size of Ag nanoparticles is large, it is possible to form PLM at two different wavelengths. This provides a possible way to extend the application of PLM.