Efficient coupling of surface plasmon polaritons to radiation using a bi-grating

A nanostructured surface in the form of a bi-grating is shown to efficientl y couple surface plasmon polaritons to free-space radiation in the visible part of the spectrum. Coupling was achieved for all propagation directions of the surface mode and the efficiency found to be independent of the propa gation direction, taking a mean value of 60% for the structure examined. Th e consequences of the findings for emissive devices that make use of surfac e plasmons are discussed. (C) 2001 American Institute of Physics.