High Bloch Surface Waves’ Biosensor Sensitivity Using All‐Dielectric Metasurface

A theoretical study of a one‐dimensional photonic crystal (1D‐PhC) [TiO 2 /MgF 2 ] 2 /TiO 2 /GaAs terminated by a dielectric metasurface consisting of periodically arranged TiO 2 nanospheres for biosensing is proposed. The p polarized incident beam and the prism couplingtechnique are employed to excite Bloch surface waves considering a low biomolecular concentration sensing medium with refractive index changing from 1.33 to 1.34 RIU. The optical properties of the metasurface layer are calculated within the effective medium approximation. The findings reveal that integrating TiO 2 nanosphere metasurfaces as the upper layer of a photonic structure allows simultaneous control of biosensor sensitivity and the reflectance curve's full width at half maximum by judiciously tuning its optical properties, relying on the filling fraction ( f ) and the size () of the TiO 2 nanospheres. Moreover, The results show that the biosensor with the metasurface performs superior to the one without it.