Non-periodic epsilon-near-zero metamaterials at visible wavelengths for efficient non-resonant optical sensing

Zelio Fusco, Mahdiar Taheri, Renheng Bo, Thanh Tran-Phu, Hongjun Chen, Xuyun Guo, Ye Zhu, Takuya Tsuzuki, Thomas P. White, Antonio Tricoli

Research output: Journal article publicationJournal articleAcademic researchpeer-review

24 Citations (Scopus)


Epsilon-near-zero (ENZ) materials offer unique properties for applications including optical clocking, nonlinear optics, and telecommunication. To date, the fabrication of ENZ materials at visible wavelengths relies mostly on the use of periodic structures, providing some manufacturing and material challenges. Here, we present the engineering of nonperiodic sodium tungsten bronzes (NaxWO3) metamaterials featuring ENZ properties in the visible spectrum. We showcase their use as efficient optical sensors, demonstrating a nonresonant sensing mechanism based on refractive index matching. Our optimized ENZ metamaterials display an unconventional blue-shift of the transmittance maximum to increasing refractive index of the surrounding environment, achieving sensitivity as high as 150 nm/RIU. Our theoretical and experimental investigations provide first insights on this sensing mechanism, establishing guidelines for the future engineering and implementation of efficient ENZ sensors. The unique optoelectronic properties demonstrated by this class of tunable NaxWO3 materials bear potential for various applications ranging from light-harvesting to optical photodetectors.

Original languageEnglish
Pages (from-to)3970-3977
Number of pages8
JournalNano Letters
Issue number5
Publication statusPublished - 13 May 2020


  • Epsilon-near-zero
  • Metamaterials
  • Nonperiodic
  • Nonresonant
  • Sensing
  • Sodium-tungsten-bronzes

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering


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