Vector field microscopic imaging of light

The behaviour of nanoscale optical devices in a variety of burgeoning research areas, such as photonic crystals(1-4), near-field microscopy(5-7), surface plasmonics(8-11) and negative index of refraction materials(12-16), is governed by strongly localized electromagnetic waves. Although such light waves are analogous to the localized electronic wavefunctions that determine the properties of solid-state quantum devices, unlike matter waves, these optical fields are vectorial in nature, and their orientation and magnitude vary on a subwavelength scale. In order to obtain a complete description of light in nanoscale devices, it is therefore crucial to be able to map the field vectors with subwavelength resolution. Thus far, local field vectors have mostly been studied by theoretical means. Here, we describe and demonstrate the first experimental mapping of vector fields of light on the nanoscale. By directly accessing the local field in its entirety, new capabilities and applications in nanophotonics may emerge.