LAUSR

Exposing metal-dielectric structures to light can result in surface plasmon excitation and propagation along the transition interface, creating a surface plasmon polariton (SPP) response. Photoemission electron microscopy (PEEM) has been used to image nanometer scale plasmonic responses in micronsized plasmonic devices [1 2]. With PEEM, optical responses can be characterized in detail, aiding in the development of new types of plasmonic structures and their applications. We show here that in thin, triangular gold platelets SPPs can be excited and concentrated within specific regions of the material. In this regard, the platelets act as receiver antennas by converting the incident light into localized excitations in specific regions of the gold platelets. The excited areas can be significantly smaller than the wavelength of the incident light (λ ≤ 1 μm). By varying the wavelength of the light, the brightness of the excited spots can be changed, and the electron emission can effectively be switched on or off for a specific region. These experimental findings are directly observed in PEEM imaging and are quantitatively evaluated using a finite-element method (FEM).