Cross-coupling effects of surface plasmon polaritons and guided mode resonances toward tunable light trapping

Achieving the precise control over high-quality ( Q ) resonances, particularly bound states in the continuum (BICs), within plasmonic metasurfaces remains a substantial challenge due to inherent material losses, which can undermine the modulation efficiency and device performance in practical settings. Here, we introduce a mechanism, termed dual-channel-driven BICs, which exploits the cross-coupling between surface plasmon polaritons and guided mode resonances to enable the delicate formation and manipulation of high- Q bound states in dissipative plasmonic platforms. This mechanism is concretized through the design of plasmonic resonant waveguide metagratings, which support controllable modal transitions from bulk-like guided modes to interface-coupled resonances, thereby facilitating the energy transfer between low-loss dielectric components and metal-associated local regimes. The proposed strategy is experimentally validated via a proof-of-concept prototype, accompanied by theoretical modeling that elucidates the governing mechanism. Furthermore, we numerically demonstrate the potential of this approach in developing high-figure-of-merit filtering and sensing. Insights derived from this work offer a versatile yet effective design framework for dissipationless manipulation of light-matter interactions at the nanoscale, thereby expanding functional capabilities of high- Q metaphotonic systems.