Near-Infrared Tunable Surface Lattice Induced Transparency in a Plasmonic Metasurface

Collective coherent scattering at the surface of a plasmonic nanoparticle array is shown to induce tunable transparency windows at the localized plasmon band. Broadband phase measurements show that the enhanced transmission is accompanied by a large anomalous dispersion, which leads to a group delay as large as similar to 8 fs within only 40 nm thick sample. This effect occurs over a wide tunable spectral range of similar to 200 nm , and appears for two distinct counter-propagating surface waves. The experimental observations are in good agreement with calculations based on coupled dipole approximation (CDA) and with finite-difference time-domain (FDTD) simulations. This study opens the door for implementation in the fields of sensing, displays, optical buffering, tunable filtering, and nonlinear optics.