Dynamically tunable multiple surface lattice resonances in overlapping gold nanodisk arrays

Arrays of noble metal nanoparticles supporting surface lattice resonances (SLRs) are promising for advanced nanophotonic devices, yet robust control and tuning of multiple resonant modes remain challenging. In this work, we fabricate overlapping gold nanodisk arrays with different lattice periods, enabling the simultaneous excitation of multiple well-defined SLRs within a single platform. By comparing transmission spectra of overlapping and isolated arrays, together with calculated near-field distributions, we confirm that each SLR is primarily governed by the structural parameters of its corresponding array. Remarkably, large variations in the relative shifts of the overlapping arrays lead to only negligible spectral changes, indicating weak inter-mode coupling and strong fabrication tolerance in this hybrid configuration. Benefiting from the coexistence of multiple high-quality resonances, the structure exhibits good multi-wavelength refractive-index sensing with a maximum sensitivity of 755 nm/RIU and a figure of merit up to 101, while maintaining stable resonance characteristics under non-ideal structural and environmental conditions. Furthermore, transferring the arrays onto a flexible substrate further enables dynamic and reversible tuning of multiple SLRs via mechanical stretching, providing active control of a complex multi-resonant system. Overall, overlapping plasmonic lattices emerge as a robust multi-band platform that bridges theoretical design and practical implementation for sensing and reconfigurable nanophotonic devices.