Electrodynamics of Conductive Oxides: Intensity-dependent anisotropy, reconstruction of the effective dielectric constant, and harmonic generation

Abstract

We study electromagnetic pulse propagation in an indium tin oxide nanolayer in the linear and nonlinear regimes. We use the constitutive relations to reconstruct the effective dielectric constant of the medium, and show that nonlocal effects induce additional absorption resonances and anisotropic dielectric response: longitudinal and transverse effective dielectric functions are modulated differently along the propagation direction, and display different epsilon-near-zero crossing points with a discrepancy that increases with increasing intensity. We predict that hot carriers induce a dynamic redshift of the plasma frequency and a corresponding translation of the effective nonlinear dispersion curves that can be used to predict and quantify nonlinear refractive index changes as a function of incident laser peak power density. Our results suggest that large, nonlinear refractive index changes can occur without the need for epsilon-near-zero modes to couple with plasmonic resonators. At sufficiently large laser pulse intensities, we predict the onset of optical bistability, while the presence of additional pump absorption resonances that arise from longitudinal oscillations of the free electron gas give way to corresponding resonances in the second and third harmonic spectra. A realistic propagation model is key to unraveling the basic physical mechanisms that play a fundamental role in the dynamics.

References in corpus (7)

• Second and Third Harmonic Generation in Metal-Based Nanostructures
• Enhanced third harmonic generation from the epsilon-near-zero modes of ultrathin films
• Negative refraction in time-varying, strongly-coupled plasmonic antenna-ENZ systems
• Harmonic Generation in Multi-Resonant Plasma Films
• Resonant, broadband and highly efficient optical frequency conversion in semiconductor nanowire gratings at visible and UV wavelengths
• Harmonic Generation from Metal-Oxide and Metal-Metal Boundaries
• Viscoelastic optical nonlocality of low-loss epsilon-near-zero nanofilms

Cited by in corpus (6)

• Roadmap on Nonlocality in Photonic Materials and Metamaterials
• Free electron nonlinearities in heavily doped semiconductors plasmonics
• Understanding the nonlinear optical response of epsilon near zero materials in the time-domain
• Harmonic generation from gold nanolayers: an old problem under a new light
• ENZ materials and Anisotropy: Enhancing Nonlinear Optical Interactions at the Nanoscale in Metal/Conducting-Oxide Multilayer Stacks
• Retrieving linear and nonlinear optical dispersions of matter: combined experiment-numerical ellipsometry in Silicon, Gold and Indium Tin Oxide