Aluminum-based quasi-3D self-aligning plasmonic metasurface with an attenuated substrate effect for high-sensitivity sensing

We propose an aluminum (Al)-based quasi-3D self-aligning plasmonic metasurface theoretically in this paper; it demonstrates a hybrid plasmon mode with narrow bandwidth and high peak-to-dip contrast that can be used for high-sensitivity sensing applications. This metasurface consists of a top Al nanodisk array elevated by a composite array of a dielectric nanopillar and Al nanohole. A moderate bulk refractive index sensitivity of up to 384 nm/RIU and an excellent surface sensitivity are achieved in this work, owing to an enhanced optical field around the top Al nanodisk readily accessing the external environment. High nanopillars here mean the top Al nanodisk is away from the bottom nanoholes, which is equivalent to suspending the top nanodisk into approximately symmetrical surroundings to eliminate adverse substrate effects. This work provides a valuable economic and high-performance sensing strategy for precise biochemical detection.