Near-field Electrical Detection of Optical Surface Plasmons and Single Plasmon Sources

Surface plasmon polaritons (SPs) are a promising basis for nanoscale photonic circuits and allow for strong coupling between single photon emitters and propagating plasmon modes. However, there is a general tradeoff between the localization of an SP and the efficiency with which it can be detected with conventional far-field optics. In this talk, I will discus a nanoscale all-electrical SP detection technique based on the near-field coupling between propagating surface plasmons and a nanowire field-effect transistor. The detection scheme consists of an Ag nanowire (NW) crossing a Ge NW field-effect transistor. The Ag NW guides SPs to the Ag/Ge junction, where they are converted to electron-hole (e-h) pairs and detected as current through the Ge NW. We use our detectors to electrically detect the plasmon emission from an individual colloidal quantum dot coupled to a SP waveguide. The detectors are highly efficient (0.1 electrons/plasmon), and a plasmonic gating effect can be used to amplify the signal even higher (up to 50 electrons/plasmon). These results enable new and efficient on-chip optical sensing applications and fulfill a key requirement for 'dark' optical frequency nanocircuits in which SPs can be generated, manipulated, and detected without involving far-field radiation.