Abstract

Plasmonic structures offer a promising platform for all-optical signal processing and ultrafast switching devices due to the achievable field enhancement [1]. In this regard, plasmonic nanowires (NWs), which are thin and narrow gold stripes of varying width, are especially interesting since they can guide surface plasmon polaritons (SPPs) and confine the electro-magnetic field in two-dimensions [2]. To date pulse propagation on these structures has been only characterized by input-output measurements [3]. Here, we present a local investigation of ultrashort pulse propagation on these plasmonic NWs using a near-field scanning optical microscope that allows us to measure the temporal as well as the spectral evolution of the pulses. We determine the group velocity of the guided mode and find strong indications of spectral reshaping due to nonlinear processes.

© 2013 IEEE