Plasmonic Metasurfaces with Quality Factors Up to 790 in the Visible Regime

Abstract

Plasmon metasurfaces supporting surface lattice resonances (SLRs) have emerged as an exciting platform for manipulating nanoscale light‐matter interactions in expanding applications. Although great progress has been achieved, the quality factors of plasmonic metasurfaces remain quite limited especially in the visible regime, hindering practical applications. This study reports an SLR‐based plasmonic metasurface with an ultrahigh quality factor that reaches 1427 in theory and 790 in experiments at 712 nm, a 240% increase over the state of the art. The quality factor of the out‐of‐plane SLR in periodic gold or silver nanorods is augmented by an order of magnitude through reducing the nanorod height from 100 to 50 nm. With these findings, this work is expected to pave the way for realizing high‐performance nanolasers, nonlinear frequency converters, and biosensors based on ultrahigh‐Q plasmonic metasurfaces.

High-Quality Resonances from Plasmonic Nanoparticle Lattices under Normal Incidence

“…Arranging metal NPs into periodical arrays can couple LSPRs of units to the diffracted waves of arrays to support surface lattice resonances (SLRs), where the radiative loss is significantly suppressed to support resonances with line widths down to 10 nm. − The narrow resonance line widths and strong field enhancement of SLRs lead to potentially high sensitivity and a low limit of detection. , Importantly, the quality (Q) of SLRs can be significantly affected by the RI environment of NP arrays, and the index match between substrate and superstrate is preferred for high-Q SLRs . However, the index-match condition can barely be satisfied for either bio- or gas sensing because RIs of aqueous solutions or gases are usually lower than those of solid substrates (glass, quartz, etc.).…”