Resonant near-field optical sources for TAR

Abstract

We have nanofabricated patterns of holes, pits, slits, and ridges in silver and gold films on quartz substrates by focused ion beam (FIB) and studied the optical properties of these resonant structures as a function of metal type, wavelength, pattern dimensions, feature dimensions, and film thickness. We find enhanced transmission due to both surface plasmon resonances and theoretically predicted waveguide resonances. The enhancement effect extends to a hole size as small as 35 nm. We also find that 35-nm-wide resonant slits can have transmission normalized to area that is 10000 times larger than through a simple circular aperture of the same dimension. Plasmon enhanced transmission was also found for compact structures composed of only one raised feature on each side of the aperture. These structures show promise for applications in thermally assisted recording (TAR).