High-sensitivity tunable Bloch surface waves' biosensor using nanocomposite cap layer

The advantage of the high versatility of the nanocomposite (Nc) materials in modeling photonic structure devices is exploited to design an optical biosensor based on Bloch surface waves (BSWs) to probe different biomolecular species. The suggested biosensor is constituted by two periods of low and high refractive indices (RIs) of alternate dielectric materials SiO${}_2$ and TiO${}_2$ capped by Ag-TiO${}_2$ Nc layer operating under the Kretschmann configuration and using p-polarized incident light. Herein, the biosensor performances are theoretically investigated in a wide range of the sensing medium RI [1.33, 1.61] using selected operating wavelengths $\lambda$ = 455, 465, 480, 500, and 600 nm to deviate a large dielectric loss of the Ag-TiO${}_2$ Nc layer. The results show that the structure sustains BSW for each wavelength in separate domains of the sensing medium RI conferring to the proposed biosensor a potential for the high-sensitive multiwavelength detection of different biomolecular entities. (© 2021 Wiley‐VCH GmbH)