SURFACE-PLASMON ENERGY GAPS AND PHOTOABSORPTION

The optical properties of a thin layer of dye deposited on a metallic grating are significantly altered by the coupling between the dye mole cules and the surface-plasmon polariton (SPP) modes of the interface. We present experimental results demonstrating that energy gaps which p rohibit the propagation of SPPs may be used to control the absorption properties of such molecules. We compare our data with theory, and we use numerical modelling to show how the effect of the gap on the absor ption may be optimized by a suitable choice of the grating profile.