Narrow quadrupolar surface lattice resonances and band reversal in vertical metal-insulator-metal gratings

TL;DR

This paper demonstrates narrow quadrupolar surface lattice resonances with high quality factors in vertical metal-insulator-metal gratings, revealing a band reversal effect and broadband tunability, with potential applications in nanolasers, nonlinear optics, and sensing.

Contribution

It reports the first observation of band reversal in SLRs supported by vertical MIM nanogratings and achieves broadband tunability of resonance lineshapes under normal and oblique incidence.

Findings

Quadrupolar SLR with linewidth of 1 nm and Q of 979 in near-infrared.

Out-of-plane dipolar SLRs with Q >= 150 under oblique incidence.

Continuous tuning of SLR wavelength over 750 nm range.

Abstract

We report narrow quadrupolar surface lattice resonances (SLRs) under normal incidence, and the observation, for the first time, of the band reversal effect of SLRs supported by a vertical metal-insulator-metal nanograting, which is embedded in a homogeneous dielectric environment. Simulation results show that under normal incidence, quadrupolar SLR with linewidth of 1~nm and high quality factor of 979 can be excited in the near-infrared regime, and that under oblique incidence, out-of-plane dipolar SLRs of relatively large quality factors (>=150) can be launched. By varying the incidence angle, the SLR wavelength can be continuously tuned over an extremely broadband range of 750 nm, covering most of the near-infrared regime, and the quality factor decreases exponentially. Remarkably, the resonance lineshape can also be dynamically tuned from an asymmetric Fano-shaped dip to a peak, a dip/peak pair, and a perfect symmetric Lorentzian peak, suggesting the appearance of the band reversal effect. We expect the high-Q SLRs with broadband tunability and tunable lineshapes will find potential applications in enhanced nanoscale light-matter interactions in nanolasers, nonlinear optics and sensing.