Abstract
Nonlinear optical phenomena are paramount in many photonic applications ranging from frequency broadening and generation of ultrashort pulses to frequency comb-based metrology. A recent trend has been to miniaturize photonic components, resulting also in a demand for small scale nonlinear components. This demand is difficult to address by using conventional materials motivating the search for alternative approaches. Nonlinear plasmonic metasurface cavities have recently emerged as a promising platform to enable nanoscale nonlinear optics. Despite steady progress, the so far achieved conversion efficiencies have not yet rivalled conventional materials. Here, we discuss our recent work to develop more efficient nonlinear metamaterials, focusing on plasmonic metasurfaces supporting collective responses known as surface lattice resonances. These resonances can exhibit very narrow spectral features, showing potential to considerably enhance nonlinear processes via resonant interactions. We demonstrate a plasmonic metasurface operating at the telecommunications C band that exhibits a record-high quality factor close to 2400, demonstrating an order-of-magnitude improvement compared to existing metasurface cavities. Motivated by this experimental demonstration, we also present numerical predictions suggesting that such metasurfaces could soon answer the existing demand for miniaturized and/or flat nonlinear components.
Highlights
Recent investigations have shown that periodic arrays of nanoparticles, known as metasurfaces, can act as optical cavities [1]
The resonances associated with individual plasmonic nanoparticles known as localized surface plasmon resonances (LSPRs) are associated with low (
Already around 10-fold improvements in Q-factors have been recently demonstrated using dielectric nanoparticle resonators [2], while dramatically higher Q-factors have been predicted to be possible by utilizing collective responses known as surface lattice resonances (SLRs) [3,4]
Summary
Recent investigations have shown that periodic arrays of nanoparticles, known as metasurfaces, can act as optical cavities [1]. Already around 10-fold improvements in Q-factors have been recently demonstrated using dielectric nanoparticle resonators [2], while dramatically higher Q-factors have been predicted to be possible by utilizing collective responses known as surface lattice resonances (SLRs) [3,4]. We demonstrate a plasmonic metasurface cavity design supporting an ultra-high-Q SLR (Q≈2400) near λ = 1545 nm [5]. Inspired by this result, we will use nonlinear discrete-dipole approximation (NDDA) to numerically investigate second-harmonic generation (SHG) from such high-Q metasurfaces [7].
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