Sub-wavelength focusing in inhomogeneous media with a metasurface near field plate

Andrew C. Strikwerda, Timothy Sleasman, William Anderson, Ra’Id Awadallah

Research output: Contribution to journalArticlepeer-review


Overcoming the diffraction limit, which enables focusing much less than the wavelength, requires tailoring the evanescent spectrum of an aperture’s field distribution. We model and simulate a corrugated near field plate, which can generate a sub-wavelength focus in inhomogeneous background media. All reactive coupling, between the metasurface near field plate and the focusing domain and among the corrugations in the metasurface, is taken into consideration with the finite element method, which we solve in combination with a constraint to generate a desired focus. Various geometries for the near field plate are considered and we demonstrate that the proposed method can effectively create a deeply sub-wavelength focus within a layered medium having properties resembling brain tissue. Such a device could find use as a detector of biological signals or for hyperthermic treatment near the skin surface.

Original languageEnglish (US)
Article number4534
JournalSensors (Switzerland)
Issue number20
StatePublished - Oct 2 2019


  • Corrugated surface
  • Diffraction limit
  • Evanescent spectrum
  • Finite element method
  • Finite element method
  • Metasurface
  • Near field plates
  • Sensing
  • Sub-wavelength focusing

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Atomic and Molecular Physics, and Optics
  • Instrumentation
  • Electrical and Electronic Engineering


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