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      Colorimetric and near-absolute polarization-insensitive refractive-index sensing in all-dielectric guided-mode resonance based metasurface

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      Author(s)
      Yıldırım, Deniz Umut
      Ghobadi, Amir
      Soydan, Mahmut Can
      Gökbayrak, Murat
      Toprak, Ahmet
      Bütün, Bayram
      Özbay, Ekmel
      Date
      2019
      Source Title
      Journal of Physical Chemistry C
      Print ISSN
      1932-7447
      Publisher
      American Chemical Society
      Volume
      123
      Issue
      31
      Pages
      19125 - 19134
      Language
      English
      Type
      Article
      Item Usage Stats
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      366
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      Abstract
      Colorimetric detection of target molecules with insensitivity to incident-light polarization has attracted considerable attention in recent years. This resulted from the ability to provide rapid output and reduced assay times as a result of color changes upon altering the environment that are easily distinguishable by the naked eye. In this paper, we propose a highly sensitive refractive-index sensor, utilizing the excitation of guided modes of a novel two-dimensional periodically modulated dielectric grating-waveguide structure. The optimized nanosensor can numerically excite guided-mode resonances with an ultranarrow linewidth (full width at half-maximum) of 0.58 nm. Sensitivity is numerically investigated by considering the deposition of dielectric layers on the structure. For a layer thickness of 30 nm, the maximum sensitivity reached as high as 110 nm/refractive index unit (RIU), resulting in a very high figure of merit of 190. The fabricated devices with 30 nm aluminum oxide and zinc oxide coatings achieved a maximum sensitivity of 235.2 nm/RIU with a linewidth of 19 nm. Colorimetric detection with polarization insensitivity is confirmed practically by a simple optical microscope. Samples with different coatings have been observed to have clearly distinct colors, while the color of each sample is nearly identical upon azimuthal rotation. Excellent agreement is obtained between the numerical and experimental results regarding the spectral position of the resonances and sensitivity. The proposed device is, therefore, highly promising in efficient, highly sensitive, almost lossless, and compact molecular diagnostics in the field of biomedicine with personalized, label-free, early point-of-care diagnosis and field analysis, drug detection, and environmental monitoring.
      Keywords
      Thickness
      Layers
      Quantum mechanics
      Resonance structures
      Polarization
      Permalink
      http://hdl.handle.net/11693/53374
      Published Version (Please cite this version)
      https://dx.doi.org/10.1021/acs.jpcc.9b04748
      Collections
      • Department of Electrical and Electronics Engineering 2421
      • Department of Physics 1494
      • Institute of Materials Science and Nanotechnology (UNAM) 928
      • Nanotechnology Research Center (NANOTAM) 457
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