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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 20, 2020
- Source ID
- 10.1038/s42005-020-00477-0
Entities
People
- Cristian Ciracì
- Muhammad Khalid
Organizations
- Air Force Office of Scientific Research