In recent years, the scanning near-field optical microscopy (SNOM) technique has proven to be a useful and powerful tool for investigating optical phenomena on the nanoscale, and for characterizing photonic devices based on nanostructures.

The instrument developed at IMT is a multi-heterodyne SNOM system, enabling polarization- and phase-resolved optical measurements with subwavelength resolution. Furthermore, the instrument is capable of operating in both the visible (532 nm) and near-infrared (1500–1600 nm) wavelength bands. As such, this instrument possesses capabilities matched by only a very few other worldwide. Our proposed work focuses on devices and applications where the particular abilities of this instrument provide important and insightful information. Specifically, we propose to investigate four classes of nanostructured photonic devices:

(1) Polarization-dependent nanostructures (including subwavelength-period gratings, resonant cavities, and other structures)
(2) Heterogeneous meta-materials composed of features at differing size scales (e.g. micro- and nanostructures)
(3) Plasmonic waveguides and cavities composed of hybrid metal/dielectric structures optimized for sensing and optical field localization applications
(4) Functionalized optical probes yielding enhanced performance (e.g. resolution, efficiency) through nanostructuring of the probe tips

Out intention is to pursue all of these efforts in conjunction with other ongoing research efforts. Areas (1) and (4) will be conducted in collaboration with external partners (principally for nanostructure fabrication), while areas (2) and (3) will link with the recently awarded research project “Optical Engineered Local Fields (ELF): design, fabrication, and characterization of optical and photonic devices based on control of local fields in nanostructures” (200021-117930). In all cases, the SNOM characterization of devices produced in other projects will provide valuable information and insight both in support of these projects as well as in enhancing our understanding of optical fields and interactions on the nanoscale.