Enhanced Nonlinear Optical Responses of Layered Epsilon-Near-Zero Metamaterials at Visible Frequencies

Abstract

Optical materials with vanishing dielectric permittivity, known as epsilon-near-zero (ENZ) materials, have been shown to possess enhanced nonlinear optical responses in their ENZ region. These strong nonlinear optical properties have been firmly established in homogeneous materials; however, it is as of yet unclear whether metamaterials with effective optical parameters can exhibit a similar enhancement. Here, we probe an optical ENZ metamaterial composed of a subwavelength periodic stack of alternating Ag and SiO${}_2$ layers and measure a nonlinear refractive index $n_2=(1.2\pm 0.1)\times 10^{-12}$ m${}^2$/W and nonlinear absorption coefficient $\beta =(-1.5\pm 0.2)\times 10^{-5}$ m/W at its effective zero-permittivity wavelength. The measured $n_2$ is $10^7$ times larger than $n_2$ of fused silica and four times larger than that the $n_2$ of silver. We observe that the nonlinear enhancement in $n_2$ scales as $1/(n_0\mathrm{Re}[n_0])$, where $n_0$ is the linear effective refractive index. As opposed to homogeneous ENZ materials, whose optical properties are dictated by their intrinsic material properties and hence are not widely tunable, the zero-permittivity wavelength of the demonstrated metamaterials may be chosen to lie anywhere within the visible spectrum by selecting the right thicknesses of the sub-wavelength layers. Consequently, our results offer the promise of a means to design metamaterials with large nonlinearities for applications in nanophotonics at any specified optical wavelength.

24 pages, includes supporting information

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Cited by in corpus (12)

• Photonics of Time-Varying Media
• Minireview on Disordered Optical Metasurfaces
• Post-2000 Nonlinear Optical Materials and Measurements: Data Tables and Best Practices
• New horizons in near-zero refractive index photonics and hyperbolic metamaterials
• Magnetic Circular Dichroism in Hyperbolic Metamaterial Nanoparticles
• Enhanced nonlinear optical response of single metal-dielectric nanocavities resonating in the near-infrared
• Ultrafast nonlinear pulse propagation dynamics in metal-dielectric periodic photonic architectures
• Observation of SQUID-like behavior in fiber laser with intra-cavity epsilon-near-zero effect
• Realization of broadband index-near-zero modes in nonreciprocal magneto-optical heterostructures
• Probing macroscopic temperature changes with non-radiative processes in hyperbolic meta-antennas
• Leveraging Epsilon Near Zero phenomena for on-chip photonic modulation
• Retrieving linear and nonlinear optical dispersions of matter: combined experiment-numerical ellipsometry in Silicon, Gold and Indium Tin Oxide