Ultrahigh-Q All-Metallic Metasurfaces with Robust Near-Perfect Absorption

Abstract

High quality-factor (Q) resonant metasurfaces have attracted significant attention due to their potential applications in cutting-edge fields of optics. However, limited by intrinsic dissipation losses, achieving both an extremely high Q factor and perfect absorption for strong light-matter interaction control in plasmonic metasurface is still highly challenging. Here, we demonstrate a plasmonic metasurface composed of symmetric double-pillars (SDPs) on a gold film, in which the flexibly tuned geometric space enables precise control over the nonlocality of dark-mode Fabry-Perot bound states in the continuum (FP-BIC) and its coupling with Rayleigh anomaly (RA)-associated lattice resonance. Based on the coupling control between these two modes, the radiative and dissipative losses are well balanced, resulting in a measured Q factor of 2180 (theoretical 2800) and absorption nearly 99%. Notably, the near-perfect absorption response is maintained over broad geometric parameter windows of SDPs (height h=70-120nm, radius r=210-280nm), while the resonance retains a consistently high Q factor throughout these ranges. This hybrid coupling strategy establishes a general framework for designing high-Q, near-critical coupling plasmonic devices for ultrasensitive sensing, narrowband filtering, and active photonics.