Characterization of plasmonic nanoantennas by Holographic Microscopy and Scanning Near-field Microscopy

We present a comparison between the optical intensity distributions above a scattering nanohole chain antenna obtained using two different imaging techniques: wide-field digital heterodyne holographic (DHH) microscopy and scanning near-field optical microscopy (SNOM). We show that these techniques have complementary possibilities and limitations but can both deliver accurate measurements of the light distribution in and across the plane of the sample in the near- to far-field transition region, at distances up to a few wavelengths around the nanostructure. The easy access to phase measurements using DHH allows for a deeper insight on the nanoantenna scattering behaviour.