Tunable ITO–metal plasmonic metamaterial channel for tailored sensing: A simulation-driven approach

We present a transparent, conductive metamaterial channel formed by embedding a triangular lattice of Au, Ag, or Cu nanodisks inside an indium–tin–oxide (ITO) slab, enabling geometry-programmable resonant absorption from 400 to 1100 nm. Using finite-difference time-domain simulations with periodic in-plane boundaries, we map how five structural parameters—disk diameter d, disk thickness t, lattice constant a, ITO thickness tc, and vertical lattice placement h—govern localized surface plasmon resonances, linewidth, and peak amplitude. Across metals, increasing t primarily blue-shifts the resonance wavelength; increasing d red-shifts the dominant localized surface plasmon resonances; larger a narrows the resonance peak FWHM; thicker ITO red-shifts the peak; and moving the lattice along strongly modulates absorbance, revealing birefringence-like asymmetry for top-down illumination. Field maps confirm dual modal hot-spots. To connect tunability with device targets, we couple the solver to a derivative-free, black-box optimization code that inversely designs the metamaterial channel to match user-defined spectra. As a case study, we realize a dual-peak response (600 nm, 10 nm FWHM; 800 nm, 80 nm FWHM; peak A = 0.5) with feasible parameter sets for Au, Ag, and Cu. The metamaterial channel is compatible with nanofabrication procedures, and its conductive host permits future electro-optic biasing for dynamic tuning. This simulation-driven framework provides a compact route to spectrally programmable absorbers for refractive-index sensing, pixel-level color filtering, photodetection, and plasmon-enhanced optoelectronics.