Observation of Ultrabroadband Striped Space-Time Surface Plasmon Polaritons

• DOI: 10.1021/acsphotonics.2c00296
• Publication Date: 2023-01-11T21:46:21Z
• Authors: Naoki Ichiji; Hibiki Kikuchi; Murat Yessenov; Kenneth L. Schepler; Ayman F. Abouraddy; Atsushi Kubo
• Keywords: Spatial light modulator

Because surface plasmon polaritons (SPPs) are waves characterized by one free transverse dimension, the only monochromatic diffraction-free spatial profiles for SPPs cosine and Airy waves. Pulsed SPP wave packets have been recently formulated that propagation-invariant localized in in-plane dimensions virtue of a tight spectral association between their temporal frequencies, which thus dubbed "space-time" (ST) SPPs. spatiotemporal structure unique to ST-SPPs, optimal launching strategy such novel plasmonic field configurations remains an open question. We present here critical step toward realizing ST-SPPs reporting observations ultrabroadband striped ST-SPPs. These each wavelength travels at prescribed angle with respect propagation axis produce periodic (striped) profile is diffraction-free. start free-space ST packet coupled ST-SPP gold-dielectric interface, unambiguously identify via axial beating detected two-photon fluorescence produced superposition incident excited surface-bound ST-SPP. results highlight viable approach efficient reliable coupling and, thus, represent first crucial realization full potential sensing imaging.