Large‐Area Plasmonic Metamaterial with Thickness‐Dependent Absorption

Abstract Plasmonic metamaterials are receiving increasing attentions due to their great ability to confine light energy at the nanoscale for perfect absorption and various applications in the near infrared and visible region. However, the common practices to achieve the tunable absorption are to adjust the morphology of plasmonic metamaterials. This strategy has a low fabrication efficiency, which limits the applications of plasmonic metamaterials. Here, the absorption efficiency and peak position of the plasmonic metamaterial consisting of Au nanohole array/SiO₂ spacer/Au film are tuned by simply controlling the thicknesses of the hexagonal Au nanohole array and the spacer layer, respectively. An ultrahigh absorption of ≈99% and a high surface‐enhanced Raman scattering (SERS) effect (with an average surface enhancement factor of 10⁶) are achieved at the desired laser wavelength. The substrate can be as large as 10 mm in diameter and shows a high uniformity for SERS detection. This work provides a simple way to flexibly tune the optical properties of plasmonic metamaterials for various promising applications such as plasmon‐mediated chemical reactions and biosensing.