Dynamical Control of Broadband Coherent Absorption in ENZ Films

Vincenzo Bruno, Stefano Vezzoli, Clayton DeVault, Thomas Roger, Marcello Ferrera, Alexandra Boltasseva, Vladimir M. Shalaev, Daniele Faccio

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Abstract

Interferometric effects between two counter-propagating beams incident on an optical system can lead to a coherent modulation of the absorption of the total electromagnetic radiation with 100% efficiency even in deeply subwavelength structures. Coherent perfect absorption (CPA) rises from a resonant solution of the scattering matrix and often requires engineered optical properties. For instance, thin film CPA benefits from complex nanostructures with suitable resonance, albeit at a loss of operational bandwidth. In this work, we theoretically and experimentally demonstrate a broadband CPA based on light-with-light modulation in epsilon-near-zero (ENZ) subwavelength films. We show that unpatterned ENZ films with different thicknesses exhibit broadband CPA with a near-unity maximum value located at the ENZ wavelength. By using Kerr optical nonlinearities, we dynamically tune the visibility and peak wavelength of the total energy modulation. Our results based on homogeneous thick ENZ media open a route towards on-chip devices that require efficient light absorption and dynamical tunability.

Original languageEnglish
Article number110
JournalMicromachines
Volume11
Issue number1
DOIs
Publication statusPublished - 20 Jan 2020

Keywords

  • Coherent perfect absorption
  • Epsilon-near-zero media
  • Light-with-light modulation
  • Refractive index change
  • Transparent conductive oxide

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Mechanical Engineering
  • Electrical and Electronic Engineering

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    Bruno, V., Vezzoli, S., DeVault, C., Roger, T., Ferrera, M., Boltasseva, A., Shalaev, V. M., & Faccio, D. (2020). Dynamical Control of Broadband Coherent Absorption in ENZ Films. Micromachines, 11(1), [110]. https://doi.org/10.3390/mi11010110