The light manipulation beyond the diffraction limit plays an invaluable role in modern physics and nanophotonics. In this work, we have demonstrated a strong coupling with a large Rabi splitting of 151 meV between bulk WS2 excitons and anapole modes in the WS2-Si nanodisk heterostructure array with nanoholes as small as 50 nm radius. This result is acquired by introducing anapole modes to suppress radiative losses to confine light into subwavelength volumes and large spatial overlapping between excitons and strong optical fields. Our work shows that anapole modes may serve as a powerful way to enhance the interaction between light and matter at nanoscales, and it should pave an avenue toward high-performance all-dielectric optoelectronic applications.

Coupling effects of surface plasmon resonance (SPR) induce changes in the wavelength, intensity, and linewidth of plasmonic modes. Here, inspired by coupling effects, we reveal an abrupt linewidth-shrinking effect in 2D gold nanohole arrays at the azimuthal angle of 45° arising from the interference of two degenerate SPR modes. We further demonstrate the biosensing capability under various excitation conditions for detecting the critical molecular biomarker of prostatic carcinoma, and achieve the maximum sensitivity at this angle. Our study not only enhances the understanding toward plasmonic resonance-linewidth shrinking, but also provides a promising strategy to greatly improve biosensing performance by light manipulation on plasmonic nanostructures.