Enhancing second-harmonic generation with electron spill-out at metallic surfaces

Abstract

Second-order nonlinear optical processes do not manifest in the bulk of centrosymmetric materials, but may occur in the angstroms-thick layer at surfaces. At such length-scales, quantum mechanical effects come into play which could be crucial for an accurate description of plasmonic systems. In this article, we develop a theoretical model based on the quantum hydrodynamic description to study free-electron nonlinear dynamics in plasmonic systems. Our model predicts strong resonances induced by the spill-out of electron density at the metal surface. We show that these resonances can boost second-harmonic generation efficiency up to four orders of magnitude and can be arbitrarily tuned by controlling the electron spill-out at the metal surface with the aid of thin dielectric layers. These results offer a possibility to artificially increase nonlinear susceptibilities by engineering optical properties at the quantum level.

References in corpus (5)

• Theory of surface plasmons and surface-plasmon polaritons
• Nonlocal optical response in metallic nanostructures
• Resonance shifts and spill-out effects in self-consistent hydrodynamic nanoplasmonics
• Nonlocal and Quantum Tunneling Contributions to Harmonic Generation in Nanostructures: Electron Cloud Screening Effects
• Longitudinal quantum plasmons in copper, gold, and silver

Cited by in corpus (9)

• Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics
• Roadmap on Nonlocality in Photonic Materials and Metamaterials
• Bright Optical Eigenmode with about 1 nm ${}^3$ Volume
• Second-harmonic generation in plasmonic waveguides with nonlocal response and electron spill-out
• Second-harmonic generation from singular metasurfaces
• Copper-based disordered plasmonic system with dense nanoisland morphology
• Electron spill-out effect on third-order optical nonlinearity of metallic nanostructure
• Observing the influence of second-harmonic tangential surface source in gold plasmonic nanostructures
• Influence of the electron spill-out and nonlocality on gap-plasmons in the limit of vanishing gaps