Subwavelength grating-based nanoplasmonic modulation for surface plasmon resonance imaging with enhanced resolution

In this study, we have investigated nanoplasmonic modulation for surface plasmon resolution imaging. Subwavelength metal grating was used to localize plasmon excitation, thereby limiting the propagation of surface plasmon. An optimum grating structure for an enhanced lateral imaging resolution was designed based on the effective medium theory. A metal grating at 400 nm period was fabricated on a metallic thin film and a BK7 glass substrate. For metal, both gold and silver were considered. Effects of other geometrical parameters such as grating thickness and orientation were also explored. The resolution enhancement was found to be more effective with silver than gold. Studies on grating thickness and orientation suggest that stronger plasmon localization produce more efficient resolution enhancement. (C) 2010 Optical Society of America