Plasmon Hybridization in Compressible Metal–Insulator–Metal Nanocavities: An Optical Approach for Sensing Deep Sub‐Wavelength Deformation
Angelica Carrara, Nicolò Maccaferri, Andrea Cerea, Angelo Bozzola, Francesco De Angelis, Remo Proietti Zaccaria, Andréa Toma
Abstract
Abstract A pressure‐induced deformation‐sensitive device (DSD) is presented based on 2D matrices of plasmonic gold nanodisks coupled to a metal thin layer through a compressible dielectric spacer, namely a deformable metal–insulator–metal (MIM) nanocavity, to report deep sub‐wavelength size variations (<λ/200). The system is characterized by two hybrid branches, which are resonant in the visible/near infrared spectral region. The fundamental mode, owing to the near‐field interaction between the plasmonic nanostructures and the metal film, exhibits a remarkable sensitivity to the gap size, exceeding that of a planar “macroscopic” optical cavity and extending its operational domain to the sub‐wavelength range, where excellent opportunities toward truly multiscale MIMs‐based pressure sensors can be envisioned. Concurrently, its intrinsic plasmonic nature synergistically combines into a single platform multi‐purpose functionalities, such as ultrasensitive detection and remote temperature readout, with practical perspectives in ultra‐compact inspection tools for structural and functional information at the nanoscale.