Dynamically Tunable High‐Q Plasmonic Fabry–Pérot Cavity Built by Particle Mirror

Abstract Plasmonic nanostructures with high quality (Q) factors or real‐time tunability have significant advantages in functional applications ranging from sensing to optical integration and quantum information processing. However, achieving both high Q factors and real‐time tunability in a single plasmonic system remains a significant challenge because of the trade‐off between structural robustness, mode coupling, and tunability. Here, a dynamically tunable high‐Q plasmonic platform based on a Fabry–Pérot (FP) cavity consisting of plasmonic particle mirrors (PPMs) embedded in a stretchable substrate are presented. High Q factors are achieved via the far‐field coupling of the localized surface plasmon resonances (LSPRs) of the PPMs. Meanwhile, the PPMs ensure the structural stability and resonance strength of the plasmonic FP cavity during real‐time mechanical tuning. Angle modulation further enhances the wavelength tunability. Additionally, the used scalable fabrication process is favorable for industrial manufacturing and real‐world applications. Based on the PPM FP platform, an active device with modulated and tunable photoluminescence (PL) peak wavelengths is demonstrated, with a strain‐controlled spectral shift of over 90 nm in the visible region. This work innovated the design of plasmonic nanostructures and provides a pathway for scalable, high‐performance plasmonic systems for functional applications.