Numerical tool to take nonlocal effects into account in metallo-dielectric multilayers

Bénédicto, Jessica; Pollès, Rémi; Ciracì, Cristian; Centeno, Emmanuel; Smith, David R.; Moreau, Antoine

doi:10.1364/josaa.32.001581

Cited by 39 publications

(33 citation statements)

References 71 publications

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“…( 9 ). Reflection spectra are calculated by solving Eqs ( 4a ), ( 4b ) and 5 using a nonlocal transfer-matrix-method 51 . We retain only second-order spatial derivatives with respect to the longitudinal direction ( z -axis) in Eq.…”

Section: Resultsmentioning

confidence: 99%

Viscoelastic optical nonlocality of low-loss epsilon-near-zero nanofilms

Ceglia

Scalora

Vincenti

et al. 2018

Sci Rep

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Optical nonlocalities are elusive and hardly observable in traditional plasmonic materials like noble and alkali metals. Here we report experimental observation of viscoelastic nonlocalities in the infrared optical response of epsilon-near-zero nanofilms made of low-loss doped cadmium-oxide. The nonlocality is detectable thanks to the low damping rate of conduction electrons and the virtual absence of interband transitions at infrared wavelengths. We describe the motion of conduction electrons using a hydrodynamic model for a viscoelastic fluid, and find excellent agreement with experimental results. The electrons’ elasticity blue-shifts the infrared plasmonic resonance associated with the main epsilon-near-zero mode, and triggers the onset of higher-order resonances due to the excitation of electron-pressure modes above the bulk plasma frequency. We also provide evidence of the existence of nonlocal damping, i.e., viscosity, in the motion of optically-excited conduction electrons using a combination of spectroscopic ellipsometry data and predictions based on the viscoelastic hydrodynamic model.

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Section: Resultsmentioning

confidence: 99%

Viscoelastic optical nonlocality of low-loss epsilon-near-zero nanofilms

Ceglia

Scalora

Vincenti

et al. 2018

Sci Rep

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“…We would like to mention that our theory takes into consideration the nonlocality effect arising from geometry of the layers, but not from the materials properties. In order to account for deviation of permittivity of the materials involved from standard descriptions, such as nonlocality of very thin metallic films, one should use the corrected expressions of ε m and ε d in the above equations. However, such case is beyond the scope of this article.…”

Section: Infinite Hmms: Nonlocal Homogenizationmentioning

confidence: 99%

Existence Conditions of High‐k Modes in Finite Hyperbolic Metamaterials

Mahmoodi

Tavassoli

Takayama

et al. 2019

Laser & Photonics Reviews

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The capability to support optical waves with very large wave vectors (high‐k) is one of the principle features of hyperbolic metamaterials (HMMs). These waves play the key role in HMM applications such as imaging and lifetime engineering. Effective medium approximation (EMA) as widely used analytical method to predict HMMs behavior, has shortcomings in calculating high‐k modes of practical structures. EMA is applicable to a subwavelength unit cell of implicitly infinite periodic structures. Using conventional EMA, in the present paper, boundary effects and spatial dispersion are taken into consideration to properly compute the high‐k modes of finite‐thickness multilayer HMMs. Applying nonlocal homogenization to stacks of alternating metal‐dielectric layers, the corresponding effective medium is examined as a high‐k waveguide sandwiched between the substrate and an ambient superstrate. The developed theory enables us to recognize two types of bulk waves coined as short‐range and long‐range propagating modes. Number of such modes as well as their cutoff conditions are quantified for the first time. Validity of the developed theory is verified both numerically by rigorous simulations of the multilayer structures with the transfer matrix method and experimentally by optical characterization of the HMMs in infrared regime.

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“…When considering nonlocality from the structural periodicity, the realistic layered structure is used in the analytical calculation. [ 43 ] When further considering nonlocality from metals, hydrodynamic model is adopted to describe the nonlocal electron screening in metals (Section S6, Supporting Information). The nonlocal electron screening refers to spatial spreading of surface charge densities over boundaries of metals, originating from the quantum repulsion of electrons or the electron gas pressure.…”

Section: Theoretical Description Of Cherenkov Radiation In Metallodiementioning

confidence: 99%

Nonlocality Induced Cherenkov Threshold

Lin

Zhang

et al. 2020

Laser & Photonics Reviews

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Cherenkov radiation is generally believed to be threshold-free in hyperbolic metamaterials owing to the extremely large photonic density of states in classical local framework. Although recent advances in nonlocal and quantum plasmonics extend our understanding of light-matter interactions in metamaterials, how such effects influence Cherenkov radiation in hyperbolic metamaterials still remains unknown. Here, it is demonstrated that effects of nonlocality add a new degree of freedom to engineer Cherenkov thresholds in hyperbolic metamaterials. The interplay between finite structural dimensions and nonlocal nature of metallic electrons results in a nonzero Cherenkov threshold. Counterintuitively, such nonlocality-induced Cherenkov threshold can be significantly smaller than the classically predicted one if the metamaterial is designed to work around the epsilon-near-zero frequency. This phenomenon is attributed to the excitation of longitudinal plasmon modes which are absent in classical electromagnetic framework. These findings apply to a general class of hyperbolic materials, including metallodielectric layered structures, nanorod/nanoribbon arrays, hyperbolic van der Waals crystals, etc.

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Numerical tool to take nonlocal effects into account in metallo-dielectric multilayers

Cited by 39 publications

References 71 publications

Viscoelastic optical nonlocality of low-loss epsilon-near-zero nanofilms

Viscoelastic optical nonlocality of low-loss epsilon-near-zero nanofilms

Existence Conditions of High‐k Modes in Finite Hyperbolic Metamaterials

Nonlocality Induced Cherenkov Threshold

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