Darkfield imaging with a plasmonic focusing lens: Antenna theory for near-field scanning optical microscopes.

摘要

It is widely known that optical imaging is not strictly limited by the Rayleigh limit. Recently, a dimple-shaped plasmonic lens has been fabricated for focusing light to the nanoscale. This dissertation will begin with a discussion of the design, fabrication, and experimental measurements of this plasmonic dimple lens.;However, one of the drawbacks of the plasmonic dimple lens is that it is an open structure, so light from the input side is scattered and introduces noise into the output of the device. This background noise may be acceptable in some applications that have an inherent threshold, such as for Heat Assisted Magnetic Recording (HAMR). In other applications, it may be desirable to have low background noise, such as for sensitive optical measurements, e.g. Near-field Scanning Optical Microscopes (NSOMs).;To this end, this dissertation subsequently presents the design, fabrication, measurement, and antenna model analysis of a novel darkfield plasmonic imaging device. There have been other approaches in literature that can also be considered to be darkfield devices, including the C-aperture structure and the bullseye pinhole. Although the device in this work can be viewed as a modification of the bullseye pinhole, this dissertation leverages the insight gained from the previously fabricated plasmonic dimple lens and couples it with an analysis via antenna theory to gain a better understanding of the limitations of NSOM probes.