Nanoscopic Visualization of Fluorescence Excitation Probability on Two-dimensional Periodical Gold Nanohole Arrays

We visualized spatial distributions of fluorescence excitation probability on a two-dimensional periodical gold nanohole array using an aperture-type scanning near-field optical microscope. Near-field fluorescence excitation images of the array revealed that the fluorescence signal is locally enhanced at internal positions on the array depending on the radiative wavelength. We also found that the enhanced fluorescence was modulated spectrally as well as spatially.