Plasmonic and Lattice Resonances in Flexible Metasurfaces for Enhanced Mechano-Optical Properties

Flexible metasurfaces integrating plasmonic nanostructures offer promising avenues for tunable optomechanical applications, yet achieving precise control over mechano-optical responses remains challenging. Here, we present a dual-step fabrication approach combining electron beam lithography with polydimethylsiloxane transfer to realize deformable Au nanostructures. Uniaxial stretching experiments revealed strain-dependent optical responses, with finite element method simulations confirming homogeneous strain distribution in the PDMS matrix. Optical characterization demonstrated distinct resonance behaviors: rigid substrate-based Au disc arrays exhibited surface lattice resonances at 575 nm, while transferred nanoring arrays on polydimethylsiloxane showed localized surface plasmon resonance shifts under strain. Notably, the nanoring array featuring thinner and larger-diameter structures, exhibited a significant plasmonic redshift of ~50 nm under 40% strain, attributed to elastic deformation of the nanoring geometry. These results highlight the critical role of structural design in enhancing mechano-optical tunability, paving the way for adaptive photonic devices and strain-sensitive sensors.