Near-field hyperspectral optical imaging.

This Minireview presents an overview of near-field hyperspectral imaging and discusses its applications. Based on a fibre-tip probe, the hyperspectral near-field optical microscope allows the simultaneous acquisition of near-field images over a broad spectral range (400 to 1000 nm), enabling the recovery of local spectroscopic information, which is essential for understanding the resonant interaction of light with nanostructured objects because the far-field and near-field spectral responses can differ significantly, as is the case for plasmonic nanostructures. The optical information is collected through local interactions with the evanescent fields at the surface of the sample; therefore, the approach provides spectroscopic information with nanoscale spatial resolution. Several applications of spectroscopic near-field microscopy are described for the visualisation of plasmonic modes in metallic nanostructures and near-field fluorescence spectroscopy.