Analytical approach for Sensitivity estimation of absorber-based RI sensor from the frequency shift slope

Document Type : Research Paper

Authors

Electrical and Computer Engineering Faculty, Semnan University, Semnan, Iran

Abstract

In this paper, a proposal is outlined for a single-narrow band metamaterial absorber designed to operate within the THz field. The structure comprises a combination of graphene and silver placed on top of SiO_2 in the subsequent layer, and silver at the bottom. Absorption is at its best at a frequency of 9.38, with 99.7% absorbance and a quality factor of 17.67. The symmetrical nature of the structure results in identical frequency and absorption percentages for both transverse electric (TE) and transverse magnetic (TM) polarizations. The frequency of the resonance is influenced by the refractive index of the medium around the absorber, indicating that the presented structure has the potential to serve as a highly sensitive sensor for refractive index measurements. We have effectively analyzed the sensor's performance and obtained a precise estimation of its maximum sensitivity by determining the slope of the resonance frequency change line resulting from variations in the refractive index. The suggestion sensor demonstrates heightened sensitivity and an admirable figure of merit (FOM) which is highly applicable in medical contexts. The refractive index typically ranges from 1.34 to 1.39 for the majority of biological samples. The potential uses of the absorber encompass high-resolution imaging and precise biomedical detecting and sensing, etc.

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Articles in Press, Accepted Manuscript
Available Online from 08 November 2025
  • Receive Date: 16 April 2025
  • Revise Date: 15 June 2025
  • Accept Date: 18 October 2025