Metal-dielectric superlenses for ultraviolet and visible light

This thesis describes a variety of experiments towards the goal of improved superlensing. This new type of lenses are based on materials with a negative refractive index, which opens up the possibility of resolving details that are significantly smaller than the wavelength of light. The results show that a resolution of 80nm can be achieved at a wavelength of 365nm, which is well below the diffraction limit, and thus proves that the superlensing effect is occurring.

The use of a superlens to translate an optical hotspot was tested. For this purpose, a silver superlens was used to image the enhanced field local field intensity from a nanoantenna array, and the results indicate a successful transfer, which opens up a number of possibilities within the fields of biological, chemical and medical diagnostics.

The use of multilayer lenses to improve imaging was also tested, for which a very low roughness lens consisting of alternating silver and silicon dioxide layers was fabricated. Unfortunately no clear conclusion could be reached, due to problems with the underlying chrome test structure. Finally, experiments were performed on the use of metal-dielectric composites as a superlensing material, due to their tunable optical properties.

The results show, that when using such composites, it is indeed possible to selectively alter the real part of the permittivity, as predicted by effective medium theory, but the loss is much higher than expected.