Optical dispersions of bloch surface waves and surface plasmon polaritons: towards advanced biosensors

Abstract

Total internal reflection ellipsometry (TIRE) method was used for the excitation and study of the sensitivity features of surface plasmon polariton (SPP) and Bloch surface waves (BSW) resonances. For the BSW generation distributed Bragg gratings were formed on the tops of the substrates (BK7 glass substrate), which had 5 bilayers of ~105 nm SiO2 and ~63 nm TiO2. The SPP sample consisted of the BK7 glass prism, a gold layer (45 nm). Numerical calculations of the optical dispersions and the experimental TIRE data have shown that SPP resonance overtake the BSW in wavelength scanning by a factor of about 17. However, for the ellipsometric parameters Fi and delta in the vicinity of excitations, the BSW sensitivity is comparable with SPP. The obtained resolution was _SPP=7.14×〖10〗^(-6) RIU, _SPP=1.7×〖10〗^(-5) RIU for the SPP and _BSW=8.7×〖10〗^(-6) RIU, _BSW=2.7×〖10〗^(-5) RIU for the BSW. The capabilities of both surface excitations are discussed from the sensitivity point of view in the design of these advanced biosensors.