PNNL

Abstract

Propagating surface plasmon polaritons (SPPs) are of particular interest for applications in nanophotonics as they offer a unique and versatile way to transport photon-initiated electrical signals in the form of coherent charge density oscillations, principally on noble metal surfaces. SPP waves have also generated fundamental interest due to their near-photon group velocity and sub-wavelength confinement. Over the last decade, photoemission electron microscopy (PEEM) has emerged as a pioneering technique for imaging surface electric fields through ultrashort laser pulse mediated electron emission, and has therefore become an indispensable tool for characterizing interfacial plasmonic phenomena. PEEM naturally provides the requisite spatial (nanometer) and temporal (femtosecond) resolution to drive and monitor SPP dynamics - a crucial step forward for the development of nanophotonic analogues of optical and electronic devices. A brief exposition of recent reports that describe commonly implemented and state-of-the-art PEEM modalities will be used to provide a perspective on the utility of these techniques for advancing our ability to initiate and characterize plasmonic phenomena at the nanoscale. In particular, we will focus on time-domain 2- and 3-pulse interferometric PEEM approaches that have enhanced the repertoire of plasmonic imaging and sensing tools with emphasis on SPP coupling, propagation, and directional manipulation.