Dual narrow surface lattice resonances in Si/SiO2 nanopillar dimer arrays

Si/SiO2 nanopillar dimer arrays are proposed to form two narrow surface lattice resonances (SLRs). One (named SLR1) mainly comes from the coupling between single Si/SiO2 nanopillar dimers' electric dipole resonance and arrays' diffraction waves. Another (named SLR2) mainly comes from the coupling between single Si/SiO2 nanopil-lar dimers' magnetic dipole resonance and arrays' diffraction waves. In the array, Si nanopillar dimers are on SiO2 nanopillar dimers, and SiO2 nanopillar dimers are on a quartz substrate. The simulated results reveal that the two SLRs' linewidths can be as small as 2.6 nm. However, for the Si/SiO2 nanopillar array without dimers, only one SLR can be formed. Compared to the SLR of the Si/SiO2 nanopillar array, the SLRs' intensity of the Si/SiO2 nanopil-lar dimer array is stronger and the SLRs' linewidth of the Si/SiO2 nanopillar dimer array is smaller. The Si/SiO2 nanopillar dimers' height and diameter, the gap of dimers, and the arrays' period are all important to regulate the two SLRs. This work is important to the design of micro-nano photonic devices based on multiple SLRs. (c) 2023 Optica Publishing Group