Materials screening and applications of plasmonic crystals

Surface plasmon polaritons are responsible for various optical phenomena, including negative refraction, enhanced optical transmission, and nanoscale focusing. Although many materials support plasmons, the choice of metal for most applications has been based on traditional plasmonic materials, such as Ag and Au, because there have been no side-by-side comparisons of different materials on well-defined, nanostructured surfaces. This article will describe how a multiscale patterning approach based on soft interference lithography can be used to create plasmonic crystals with different unit cell shapes-circular holes or square pyramids-which can be used as a platform to screen for new materials. The dispersion diagrams of plasmonic crystals made from unconventional metals will be presented, and the implications of discovering new optical coupling mechanisms and protein-sensing substrates based on Pd will be described. Finally, the opportunities enabled by this plasmonic library to dial into specific resonances for any angle or material will be discussed.