Direct mapping of plasmonic coupling between a triangular gold island pair

Local plasmonic coupling between a triangular gold island pair is observed with high spatial resolution (similar to 10 nm) by an apertureless scanning near-field optical microscope. The measured local field distribution is fully reproduced by three dimensional numerical simulations. Our results show a strong near-field coupling between two adjacent gold triangles, which gives direct evidence to the local field enhancement in plasmonic nanoantenna effect. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3700725]