Plasmonic Quasi-Bound States in Continuum Facilitated Bulk Photovoltaic Effect for Spectrally Selective and Polarization-Sensitive Bipolar Photodetection

Bulk photovoltaic effect (BPVE), while promising for enabling self-powered and polarization-sensitive photodetection, faces material constraints limited to ferroelectrics, chalcogenides, and topological insulators. Although recent advances in metasurface-engineered graphene devices have demonstrated artificial BPVE, these systems typically exhibit broadband responses and lack spectral selectivity. To address these challenges, we present an asymmetric metasurface-integrated graphene photodetector leveraging bound states in the continuum (BICs) for narrowband near-infrared (NIR) operation. Through strategic implementation of nonparallel gold nanorod pairs on graphene, we achieve concurrent symmetry breaking for both BIC modulation and BPVE activation. This configuration generates an asymmetric electric field intensity with over 3 orders of magnitude enhancement, establishing a localized Seebeck coefficient gradient that drives directional hot-carrier transport in graphene. The resulting photodetector demonstrates polarization-dependent bipolar photocurrents with unique spectral selectivity, achieving a characteristic negative polarization ratio of −1 in the NIR regime. Capitalizing on the photocurrent polarity reversal mechanism, we further implement a polarization-encoded optical communication scheme. Our work establishes a paradigm for multifunctional optoelectronic integration by synergizing plasmonic quasi-BIC engineering with BPVE principles, paving the way for miniaturized on-chip devices integrating spectral discrimination, polarization sensitivity, and self-powered operation.