Controlling Localized Photoemission of Triangular Gold Antennas Through Polarization

Photoemitters and plasmonic devices may become critical elements of photonics, which is being developed to augment or replace traditional electronic circuits. In recently studied devices, electrons are photo-emitted from a metallic material through exposure to femtosecond laser pulses in a non-linear, multi-photon process. Typically, the incident laser light will undergo diffraction at the edges of the metal layer, exciting surface plasmon polaritons (SPP) along the top and bottom surfaces. In thin, triangular gold platelet antennas the SPPs can be concentrated within specific regions of the material, resulting in localized photoemission in areas significantly smaller than the wavelength of the light. Experimentally, these effects can be imaged via photoemission electron microscopy (PEEM) [1]. By using finite-difference time-domain (FDTD) based modeling, these experimental results can be analyzed in detail, dependencies characterized, and new results predicted. We show here that by varying the polarization of the incident light, the intensity of the emission can be directly controlled; effectively turning it on or off. In the future, our results will allow us to identify the mechanisms behind the photoemission and to determine new ways to control the plasmonic and electronic properties of nanoscale devices.