Imaging three-dimensional light propagation through periodic nanohole arrays using scanning aperture microscopy.

The authors introduce a technique for three-dimensional (3D) imaging of the light transmitted through periodic nanoapertures using a scanning probe to perform optical sectioning microscopy. For a 4×4 nanohole array, the transmitted light displays intensity modulations along the propagation axis, with the maximum intensity occurring at 450 μm above the surface. The propagating fields show low divergence, suggesting a beaming effect induced by the array. At distances within 25 μm from the surface, they observe subwavelength confinement of light propagating from the individual nanoholes. Hence, this technique can potentially be used to map the 3D distribution of propagating light, with high spatial resolution.