Diffraction-grating-enhanced light emission from tunnel junctions

We report the observation of highly polarized, angle-tunable visible light emission from Al-AlOx-Ag tunnel junctions fabricated on holographic gratings. From the angular dependence of the emission frequency we identify the electromagnetic mode responsible for the emission. The mode is surface plasmonlike with a dispersion that closely follows the light line. This is in contrast to the much lower phase velocity "junction" mode believed responsible for the light emission on surface-roughened tunnel junctions. We argue that both modes should be considered in describing the emission from these devices.