Spatiotemporal characterization and control of lightfield nanolocalization on metallic nanostructures by nonlinear-PEEM

Abstract

The excitation of surface plasmons in metallic nanostructures by resonant ultrashort femtosecond light pulses produces interesting phenomena such as optical field nanolocalization, nanoscale electric field enhancement and ultrafast subfemtosecond beating of the plasmon eigenmodes. Nonlinear two-photon photoemission electron microscopy has proven to be a powerful tool for spatiotemporal characterization of such effects on the nanoscale below the optical diffraction limit. As a step toward using intense, few-cycle 4 femtosecond laser pulses to excite and control surface plasmons, we report on the multiphoton-photoemission electron microscopy experiments on lithographically-fabricated gold nanostructures excited by these few-cycle laser pulses. In addition, the effects of the shape and size of silver plasmonic structures, as well as the polarization of the excitation source are examined in the two-photon photoemission induced by picosecond laser pulses. Potential approaches toward spatiotemporal control of lightfield nanolocalization are described.