Effective medium approximation for deeply subwavelength all-dielectric multilayers: when does it break down?

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    Abstract

    We report on theoretical analysis and experimental validation of the applicability of the effective medium approximation to deeply subwavelength (period ⩽λ/30) all-dielectric multilayer structures. Following the theoretical prediction of the anomalous breakdown of the effective medium approximation [H. H. Sheinfux et al., Phys. Rev. Lett. 113, 243901 (2014)] we thoroughly elaborate on regimes, when an actual multilayer stack exhibits significantly different properties compared to its homogenized model. Our findings are fully confirmed in the first direct experimental demonstration of the breakdown effect. Multilayer stacks are composed of alternating alumina and titania layers fabricated using atomic layer deposition. For light incident on such multilayers at angles near the total internal reflection, we observe pronounced differences in the reflectance spectra (up to 0.5) for structures with different layers ordering and different but still deeply subwavelength thicknesses. Such big reflectance difference values resulted from the special geometrical configuration with an additional resonator layer underneath the multilayers employed for the enhancement of the effect. Our results are important for the development of new homogenization approaches for metamaterials, high-precision multilayer ellipsometry methods and in a broad range of sensing applications.
    Original languageEnglish
    Title of host publicationProceedings of SPIE
    Number of pages8
    Volume9883
    PublisherSPIE - International Society for Optical Engineering
    Publication date2016
    DOIs
    Publication statusPublished - 2016
    EventSPIE Photonics Europe 2016 - SQUARE Brussels Meeting Centre, Brussels, Belgium
    Duration: 3 Apr 20167 Apr 2016

    Conference

    ConferenceSPIE Photonics Europe 2016
    LocationSQUARE Brussels Meeting Centre
    Country/TerritoryBelgium
    CityBrussels
    Period03/04/201607/04/2016

    Bibliographical note

    Copyright 2016 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

    Keywords

    • Effective Medium Approximation
    • Metamaterial
    • Subwavelength multilayers
    • Atomic layer deposition
    • Homogenization

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