Unleashing\nGiant Forster Resonance Energy Transfer\nby Bound State in the Continuum

Förster resonance energy transfer (FRET), driven\nby dipole–dipole\ninteractions (DDIs), is widely utilized in chemistry, biology, and\nnanophotonics. However, conventional FRET is ineffective at donor–acceptor\ndistances exceeding 10 nm and measurements suffer from low signal-to-noise\nratios. In this study, we demonstrate significant FRET enhancement\nand extended interaction distances under ambient conditions by utilizing\na bound state in the continuum (BIC) mode within a dielectric metasurface\ncavity. This enhancement is achieved by leveraging the ultrahigh quality\nfactors, minimal material absorption, and nonlocal effects associated\nwith the BIC mode. Spectrally and angularly resolved photoluminescence\n(PL) lifetime measurements reveal that the BIC mode significantly\nincreases the FRET rate and interaction distance. The FRET rate is\nenhanced by up to 70-fold, and the interaction distance is significantly\nboosted by over an order of magnitude, reaching ∼100 nm. These\nfindings offer valuable insights for achieving long-range, high-efficiency\nFRET and collective DDIs using loss-less dielectric metasurfaces.