Low-cost plastic plasmonic substrates for operation in aqueous environments

We report a novel design of a multilayer stack to attain surface-plasmon-coupled emission (SPCE) enhancements in liquid medium. Variation in thickness of the multilayer affects the position and depth of resonance plasmon dips. Numerical investigation resulted in an optimal stack configuration that supports long-range surface plasmons. SPCE substrates were prepared on plain BK7 glass and Teflon-AF coated polycarbonate (PC-T) substrates by modifying their surface functionalities using plasma etching. The changes in refractive indices due to the presence of the fluoropolymer layer help reduce the SPCE exit angle from α = 75° (plain BK7) to α = 60° (PC-T) in water without requiring specialized optics.