Enhanced resolution beyond the Abbe diffraction limit with wavelength-scale solid immersion lenses.

The solid immersion lens (SIL) is a well-developed near-field optical device for imaging and data storage. Recent experiments have demonstrated high-quality imaging beyond the diffraction limit by nanoscale lenses in an SIL-type implementation [Nature 460, 498 (2009)]; we call these nSIL. A question arises as to what resolution is obtainable with an nSIL. From full three-dimensional, finite-difference time-domain calculations, we demonstrate that the FWHM of the focal spot of an objective-lens-nSIL system can be reduced by greater than 25% compared to a regular macroscopic SIL.