Probing Coherent Surface Plasmon Polariton Propagation Using Ultrabroadband Spectral Interferometry

Abstract

Surface plasmon polaritons (SPPs) are shortlived evanescent waves that can confine light at the surface of metallic nanostructures and transport energy over mesoscopic distances. They may be used to generate and process information encoded as optical signals to realize nanometerscale and ultrafast all-optical circuitry. The propagation properties of these SPPs are defined by the geometry and composition of the nanostructure. Due to their short, femtosecond lifetimes, it has so far proven difficult to track this propagation in the time domain and to directly study the effect of the propagation on the shape of a coherent SPP wavepacket. Here, we introduce an ultrabroadband far-field spectral interferometry method, allowing for the reconstruction of the plasmonic field in the time domain, to characterize coherent SPP propagation in metallic nanostructures. Group velocity and dispersion of SPPs are determined with high precision in a broad frequency range in the visible and near-infrared region, and the propagating SPP field is tracked with high time resolution over distances of tens of micrometers. Our results shed new light on the interplay between nanostructure geometry and coherent SPP propagation and hence are important for probing plasmon−matter interactions as well as for implementations of ultrafast plasmonic circuitry.

Nanoscale Broadband Deep-Ultraviolet Light Source from Plasmonic Nanoholes

“…The use of wideband light sources is required to better understand LSP’s linear and nonlinear properties. Here we excite the LSP resonances of rectangular nanoholes on a gold film by a broadband Ti:sapphire oscillator.…”

Generating Ultrabroadband Deep-UV Radiation and Sub-10 nm Gap by Hybrid-Morphology Gold Antennas

“…The phase variation is equivalent to the introduction of a 200 μm of fused silica. This is attributed to an additional phase shift induced by the plasmons. − Therefore, an additional negative dispersion compensation is required for the nanostructures. Compared to the THG emission from the bare sapphire substrate, which is about 15 nm wide (fwhm), the plasmonic structures obviously generate a nearly three times broader spectrum of about 40 nm (fwhm), which supports few cycle pulses down to only 3.1 fs.…”

Plasmonic nanofocusing spectral interferometry

“…The fringe spacing and fringe contrast both gradually decrease with increasing distance. These SIs [55][56][57][58] reflect the interference between the grating-coupled SPP field that is incident on the protrusion and scattered towards the detector (E 1 ) and the backpropagating SPP field that is coupled into the far field (E 2 ). The SI, S(ω) = | E 1 (ω) + E 2 (ω) | 2 , thus probes the interference between the incident field E s1 and the backpropagating SPP field E s2 at the position of the scatterer.…”