Optimization of Metal Quality for Grating Coupled Surface Plasmon Resonance

Silver coated gratings were fabricated using an ultraviolet nanoimprint process followed by an electron beam evaporation method. A SiO2 mold was used for the nanoimprint. The long and short range surface plasmon modes could be observed by adjusting the refractive indices of top and bottom surface layers of silver grating. The surface roughness (Ra) of silver affected the surface plasmon resonance characteristics. The deep and narrow plasmon coupling dip could be observed for the silver film with Ra less than 2 nm.