Plasmonic Grating-Enabled Broadband Polarization-Sensitive Detection in Isotropic Bi₂O₂Se

Two-dimensional Bi₂O₂Se possesses high mobility and broadband absorption, yet its tetragonal symmetry prevents intrinsic polarization-sensitive detection. Here, we integrate one-dimensional Au gratings onto epitaxial Bi₂O₂Se films to break this in-plane isotropy. This metasurface enables polarization-selective localized surface plasmon resonance excitation, inducing anisotropic near-field enhancement and polarization-dependent photoresponse from 520 to 1060 nm. Critically, the enhanced photoresponse is consistent with Au-induced interfacial potential modulation that may assist carrier separation and collection, yielding millisecond response, responsivity of 27.7 mA/W at 520 nm, and detectivity of 1.59 × 10¹⁰ Jones. polarization extinction ratio reach ≥1.6 across the entire band. These results demonstrate that one-dimensional plasmonic structuring can impart polarization sensitivity to intrinsically isotropic epitaxial Bi₂O₂Se, enabling polarization-resolved photodetection at Broadband spanning the visible to near-infrared range.