Interaction of metallic structures with electromagnetic radiation is a living topic of near-field optics including plasmonics and nanophotonics. The field-matter interaction treated on the subwavelength scale opens the path to a wide range of applications, among others to different variants of the surface enhanced spectroscopy. In this thesis we theoretically describe how the near-field properties of the metallic structures can be accessed by a probe of near-field scanning optical microscope. Formation of the signal in the near-field microscopy utilizing weakly interacting probes is discussed. Further, we elucidate the mechanism of the surface enhanced infrared spectroscopy. We utilize a model example of linear dipole antennas interacting with sample structures. A close connection is found between the spectroscopic signal and signal of the scattering type near-field optical microscopy.

The infrared and millimeter-wave portions of the spectrum both have their advantages for development of imaging systems. Because of the difference in wavelengths, infrared imagers offer inherently high resolution, while millimeter-wave systems have better penetration through atmospheric aerosols such as fog and smoke. Shared-aperture imaging systems employing a common focal-plane array that responds to both wavebands are desirable from the viewpoint of overall size and weight. We have developed antenna-coupled sensors that respond simultaneously at 30 THz and at 94 GHz, utilizing electron-beam lithography. Slot-antenna designs were found to be particularly suitable for coupling radiation into metal-oxide-metal (MOM) tunnel diodes at both frequencies. The MOM diodes are fabricated in a layered structure of Ni-NiO-Ni, and act as rectifying contacts. With contact areas as low as 120 nm × 120 nm, these diodes have time constants commensurate with rectification at frequencies across the desired millimeter-wave and infrared bands. One challenge in the development of true focal-plane array imagers across this factor-of-300 bandwidth is that the optimum spatial sampling interval on the focal plane is different in both bands. We have demonstrated a focal plane with interleaved infrared and millimeter-wave sensors by fabricating infrared antennas in the ground plane of the millimeter-wave antenna. Measured performance data in both bands are presented for individual antenna-coupled sensors as well as for devices in the dual-band focal-plane-array format.