ABSTRACT
Scanning Near-field Optical Microscopy (SNOM) is the leading instrument used to image optical fields on the nanometer scale. A metal-coating is typically applied to SNOM probes to define a subwavelength aperture and minimize optical leakage, but the presence of such coatings in the near field of the sample can often cause a substantial change in the sample emission properties. For the first time, the authors demonstrate near-field imaging on a metal substrate with a metal-free probe made from a novel structured optical fiber, designed to maximize optical throughput and potentially remove the need for the metal.
ABSTRACT
We experimentally and computationally demonstrate high transmission through arrays of coaxial apertures with different geometries and arrangements in silver films. By studying both periodic and random arrangements of apertures, we were able to isolate transmission enhancement phenomena owing to surface plasmon effects from those owing to the excitation of cylindrical surface plasmons within the apertures themselves.
ABSTRACT
Here the behavior of periodic annular aperture arrays in a perfectly conducting film is considered as the geometry of the apertures is varied. Using a previously developed rigorous electromagnetic modal method it is shown that the far-field transmission spectrum approaches that for an array of circular apertures as the stop size approaches zero. In the case where the diameter of the apertures is significantly less than that of the period of the array, the behavior of the array changes gradually from one where the predominant features in the spectra are due to the excitation of a waveguide resonance to one exhibiting 'extraordinary transmission'.
