Quasi-Bound States in the Continuum in PDMS-Supported Silicon Metasurfaces

Quasi-bound states in the continuum (quasi-BICs) in all-dielectric metasurfaces support high-Q resonances that are highly sensitive to structural symmetry and radiative coupling. Most previous studies have focused on static configurations on rigid substrates, whereas the behavior of quasi-BIC modes in the presence of low-index polymer supports remains less explored. In this work, we present a numerical investigation of quasi-BIC resonances in a silicon nanodimer metasurface on a polydimethylsiloxane (PDMS) substrate by systematically analyzing the effects of in-plane asymmetry, light incident angle and substrate thickness variation on their spectral position and quality factor. The results demonstrate pronounced tuning of the resonance wavelength and linewidth while preserving the characteristic high-Q behavior of quasi-BIC modes. This study establishes PDMS-supported silicon nanodimers as a viable platform for quasi-BIC metasurfaces and provides guidelines for future mechanically or chemically reconfigurable infrared devices based on polymer substrates.