Negative Refraction in Time-Varying Strongly Coupled Plasmonic-Antenna–Epsilon-Near-Zero Systems
Vincenzo Bruno, Clayton DeVault, Stefano Vezzoli, Zhaxylyk A. Kudyshev, Tahiyat Huq, Sandro Mignuzzi, Andrea Jacassi, Soham Saha, Yash D. Shah, Stefan A. Maier, David R. S. Cumming, Alexandra Boltasseva, Marcello Ferrera, Matteo Clerici, Daniele Faccio, Riccardo Sapienza, Vladimir M. Shalaev
Abstract
Time-varying metasurfaces are emerging as a powerful instrument for the dynamical control of the electromagnetic properties of a propagating wave. Here we demonstrate an efficient time-varying metasurface based on plasmonic nano-antennas strongly coupled to an epsilon-near-zero (ENZ) deeply subwavelength film. The plasmonic resonance of the metal resonators strongly interacts with the optical ENZ modes, providing a Rabi level spitting of ∼30%. Optical pumping at frequency ω induces a nonlinear polarization oscillating at 2ω responsible for an efficient generation of a phase conjugate and a negative refracted beam with a conversion efficiency that is more than 4 orders of magnitude greater compared to the bare ENZ film. The introduction of a strongly coupled plasmonic system therefore provides a simple and effective route towards the implementation of ENZ physics at the nanoscale.