Analysis of refractive index sensing properties of independently and arbitrarily tunable multiplexed compound supercell gratings.

A major challenge in resonance regulation remains the independent and arbitrary tuning of resonance position and intensity in conventional micro- and nanostructures, due to mode overlap and limited degrees of freedom. Here, we propose a three-dimensional (3D) multi-periodic supercell (3D-MPSC) structure that enables efficient and independent control of optical properties across multiple resonant wavelengths. By leveraging waveguide resonant modes and precisely adjusting structural parameters, the enhanced local field can be confined to individual unit cells, enabling decoupled and arbitrary tuning of multiple resonances. Under transverse-magnetic (TM) polarization, increasing the refractive index from n = 1.05 to n = 1.10 (Δn = 0.05) yields resonance-rate changes ΔR1 = 0.13 and ΔR2 = 0.03, with resonance-wavelength shifts Δλ1 = 7.4 nm and Δλ2 = 10.2 nm. The corresponding refractive-index sensitivities are S1 = 149 nm/RIU and S2 = 204 nm/RIU. This work offers new design strategies for photoluminescent materials and enables the integration of multiple devices—such as multi-band, independently tunable optical filters, sensors, and photodetectors—over a broad spectral range, enabling simultaneous detection of multiple analytes.