Numerical Study on a Bound State in the Continuum Assisted Plasmonic Refractive Index Sensor

Plasmonic sensors have attracted intensive attention due to their high sensitivity. However, intrinsic metallic loss, plasmonic usually a large full width at half maximum (FWHM) that limits the wavelength resolution. In this paper, we numerically investigate and propose dielectric grating-assisted device, leveraging bound states in continuum (BIC) effect suppress FWHM of resonance. We initiate quasi-SP-BIC modes 1559 nm 1905 wavelengths by slightly tilting incident angle 2° break symmetry, featuring narrow linewidth 1.8 0.18 these two wavelengths, respectively. Refractive index sensing has also been investigated, showing sensitivity 938 nm/RIU figure merit (FOM) 521/RIU even higher 1264 FOM 7022/RIU nm.