Excitation of Surface Plasmon-Polariton Wave at Both Interfaces of a Silver Thin Film in Two-Layer Kretschmann Geometry

In this work, a TiO2-Ag composite structure was fabricated by combination of physical vapor deposition and oblique angle deposition. The nanostructure of the TiO2 columnar thin film was analyzed using the field emission scanning electron microscopy. The excitation of the surface plasmon-polariton waves was studied using an optical setup that is called the two-layer Kretschman geometry. The results showed that two surface plasmon-polariton modes are propagated for TiO2 dielectric thin film at oblique deposition that they are related to metal-air and TiO2-metal interfaces. The surface plasmon-polariton modes were more localized on interfaces at glancing angles of incident flux vapor. In normal incident of flux vapor only, one surface plasmon-polariton mode can be excited at interface of metal-air. Also, the simulation results by transfer matrix method showed good agreement with the experimental results. The results of this research may be applied in simultaneous sensing of the different molecules, chemical species, and nanoparticles with different sizes.