Observation of nonlocal optical response in doped-cadmium-oxide epsilon-near-zero thin films

Domenico De Ceglia, Michael Scalora, Maria A. Vincenti, Salvatore Campione, Kyle Kelley, Jon-Paul Maria, Gordon A. Keeler, Ting S. Luk

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We study optically-excited nonlocalities in thin films of doped cadmium oxide. Although these effects are usually weak and hardly observable in the optical response of noble metals, the free-electron nonlocality is significantly increased in doped-cadmium-oside thin films. This increase is due mainly to: (i) low electron scattering rates; and (ii) interband transitions due to valence-band and inner-core electrons that occur far from the epsilon-near-zero frequency. The optical nonlocality manifests itself in the blueshift of the epsilon-near-zero mode, an associated reflectance dip, and the onset of higher-order modes. We model the structure using a generalized hydrodynamic theory that treats the free electrons in the film as a viscoelastic fluid. We demonstrate that both elasticity and viscosity play a significant role in the optical response of the film. The elasticity induces optical resonances associated with the longitudinal pressure modes of the free-electrons fluid, leading to a thickness-dependent permittivity. The viscosity introduces nonlocal damping and additional losses. In our view, this demonstration furthers our understanding of the dynamics of light-matter interactions, and adds a significant stepping stone toward the ability to effectively manipulate linear and nonlinear optical properties at the nanoscale.

Original languageEnglish (US)
Title of host publicationProceedings of the 2017 19th International Conference on Electromagnetics in Advanced Applications, ICEAA 2017
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages1462-1464
Number of pages3
ISBN (Electronic)9781509044511
DOIs
StatePublished - Oct 11 2017
Event19th International Conference on Electromagnetics in Advanced Applications, ICEAA 2017 - Verona, Italy
Duration: Sep 11 2017Sep 15 2017

Other

Other19th International Conference on Electromagnetics in Advanced Applications, ICEAA 2017
CountryItaly
CityVerona
Period9/11/179/15/17

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All Science Journal Classification (ASJC) codes

  • Electrical and Electronic Engineering
  • Instrumentation
  • Radiation

Cite this

De Ceglia, D., Scalora, M., Vincenti, M. A., Campione, S., Kelley, K., Maria, J-P., Keeler, G. A., & Luk, T. S. (2017). Observation of nonlocal optical response in doped-cadmium-oxide epsilon-near-zero thin films. In Proceedings of the 2017 19th International Conference on Electromagnetics in Advanced Applications, ICEAA 2017 (pp. 1462-1464). [8065557] Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/ICEAA.2017.8065557