Thin Dielectric Layers Evaluation Using Tunable Split-Ring Resonator Based Metasurface in THz Frequency Range

Featured Application A potential application of the proposed work is the quality evaluation of thin (in the order of several micrometers) dielectric foils/layers, e.g., during fabrication. The paper presents the evaluation of thin dielectric layers using a tunable split-ring resonator-based metasurface in the THz frequency range. Tunable unit cells of a metasurface allow its resonant frequency variation using some external excitation. This can be done in various ways. In this work, the behavior of such a metasurface is investigated by monitoring the resonant frequency value when the unit cell geometry is changed. Such behavior is utilized for the quality evaluation of a thin dielectric layer placed in vicinity of a metasurface. A change in dielectric permittivity noticeably affects the resonant frequency of a metasurface. In order to examine the state of the material under test, finite element method simulations were made for a 15 mu m thin layer. As a result, the approximation-based relations between resonant frequencies (obtained for various geometries of structural element-in tunability range) and dielectric parameters of the examined material were derived. These relations carry more information than in the case of just one resonant frequency (the case of a non-tunable metasurface) and can be utilized for permittivity evaluation.

Automated summary

This paper presents a method for quality evaluation of thin dielectric layers using a tunable split-ring resonator-based metasurface. By monitoring the resonant frequency of the metasurface when the unit cell geometry changes, the quality of the thin dielectric layer placed near the metasurface can be evaluated. The study derives the approximation-based relations between resonant frequencies and dielectric parameters, providing more information for permittivity evaluation.