Regular Article – Optical Phenomena and Photonics
Ultra-narrow band perfect absorber for sensing applications in the visible region
Advanced Simulation Lab, Centre of Relevance and Excellence in Fiber Optics and Optical Communication, Delhi Technological University, 110042, Delhi, India
2 Hansraj College, University of Delhi, 110007, Delhi, India
Accepted: 16 February 2023
Published online: 15 March 2023
Plasmonics is widely used for converting electromagnetic radiation into energy and confining electromagnetic radiation below the diffraction limit. However, the ultra narrowband and high electromagnetic field cannot be obtained simultaneously because of resistive loss and radiation damping in the metals. In this article, a metallic ultra-narrow band perfect absorber has been proposed consisting of an array of four squares on a silver layer. The structure shows more than 99% absorption and full width at half maxima less than 2 nm at resonance wavelength. The absorption mechanism has been revealed by calculating electric and magnetic field profiles. The dependence of the structure on the geometrical parameters has been studied and the structure has thus been optimized at 692 nm i.e. in the visible range of frequency. The proposed structure is then investigated for sensing application. The structure shows high sensitivity of 680 nm/RIU in the visible range of wavelength and a high figure of merit of 348.72.
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