Slow-mode surface plasma oscillations in layered structures

Abstract

Dispersion and intensity of slow-mode surface plasmons were determined for aluminum-- oxide--noble-metal (silver, gold, and copper) planar tunnel structures in the energy range 0.1--3.5 eV, with use of current-fluctuation theory. Experimentally determined complex dielectric functions of metals were used in the calculations. An optimum was found on the energy scale for future experiments on slow-mode plasmons at 1.3 eV (\ensuremath{\lambda}\ensuremath{\sim}1 \ensuremath{\mu}m) where their power-density function has a relative (in silver) or absolute (in gold and copper) maximum. Three types of experiments are proposed where layered structures deposited onto grating substrates of 100-nm periodicity have to be used. Expected light intensities can exceed by 2 orders of magnitude the intensities measured so far from fast-mode surface plasmons.