Optical Dispersions of Bloch Surface Waves and Surface Plasmon Polaritons: Towards Advanced Biosensors

The 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 (BSWs) resonances. For the BSWs generation distributed Bragg gratings were formed on the tops of the substrates (BK7 glass substrate), which had six bilayers of similar to 120 nm SiO2 and similar to 40 nm TiO2 and 40 nm of TiO2 on the top. The SPP sample consisted of the BK7 glass prism and a gold layer (45 nm). Numerical calculations of the optical dispersions and the experimental TIRE data have shown that SPP resonance overtake the BSWs in wavelength scanning by a factor of about 17. However, for the ellipsometric parameters Psi and Delta in the vicinity of excitations, the BSW sensitivity is comparable with SPP. The obtained resolutions were Delta SPP=7.14x10-6RIU, Psi SPP=1.7x10-5RIU for the SPP and Delta BSW=8.7x10-6RIU, Psi BSW=2.7x10-5RIU for the BSW. The capabilities of both surface excitations are discussed from the sensitivity point of view in the design of these advanced biosensors.