Two-mode radiation from light-emitting tunnel junctions

Abstract
We have employed a prism coupler to cause two independent surface-plasmon polariton modes of a metal-insulator-metal tunnel junction to radiate. We have characterized the radiative coupling of the modes by attenuated-total-reflection spectrometry and measured the angular dependence of the emitted light. Each of the radiative modes is supported by one of the metal surfaces farthest from the tunneling barrier. A model calculation suggests that the modes are excited at the surfaces that support them.