Enhanced Propagating Surface Plasmon Signal Detection

Overcoming the dissipative nature of propagating surface plasmons (PSPs) is a prerequisite to realizing functional plasmonic circuitry, in which large-bandwidth signals can be manipulated over length scales far below the diffraction limit of light. To this end, we report on a novel PSP-enhanced signal detection technique achieved in an all-metallic substrate. We take advantage of two strategically spatiotemporally separated phase-locked femtosecond laser pulses, incident onto lithographically patterned PSP coupling structures. We follow PSP propagation with joint femtosecond temporal and nanometer spatial resolution in a time-resolved nonlinear photoemission electron microscopy scheme. Initially, a PSP signal wave packet is launched from a hole etched into the silver surface from where it propagates through an open trench structure and is decoded through the use of a timed probe pulse. FDTD calculations demonstrate that PSP signal waves may traverse open trenches in excess of 10 μm in diameter, thereby al...