Optimizing the Sensing Efficiency of Plasmonic Based Gas Sensor
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Optimizing the Sensing Efficiency of Plasmonic Based Gas Sensor Sumera Afsheen1 · Anam Ahmad2 · Tahir Iqbal2 · Mohsin Ijaz2 · Almas Bashir2 Received: 15 April 2020 / Accepted: 2 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract This paper investigates the behavior of the surface plasmon polaritons (SPPs) on dielectric-metal interface using Ag thin film on glass substrate. The Kretschman configuration, which is sensitive to the change in the local environment adjacent to Ag thin film, has been modeled using COMSOL Multiphysics, RF module. The graphical presentation for the change in excitation spectra of SPPs on the interface has been analyzed by adjusting the incident angle greater than critical angle of glass while keeping the thickness of Ag thin film constant. The cross-sectional view reveals that the maximum amplitude of electric field occurs at 43° incidence. In order to study the behavior of resonance dip at varying refractive index (from 1.00 to 1.01), the reflection spectra for transverse magnetic (TM) mode of incident light has been extracted using far-field analysis. To further explore the sensitivity and resolution of the device, nm/RIU is collected by using the change in the wavelength (nm) of SPPs for minimum reflection. The remarkably maximum sensitivity of the device has been calculated as 23,000 nm/ RI and Q value calculated for Ag-based sensing is 13. Keywords Kretschman configuration · Ag thin film · Sensitivity · Q value · Surface plasmon polaritons
Introduction Total internal reflection is important for the confinement and propagation of light through dielectric media. But it is to be known that light not totally reflects back to that medium instead some of its part propagate in the form of Evanescent wave. This Evanescent wave has much importance in the field of plasmonics as these waves are not only used to generate SPPs but are efficiently used to control the sensitivity of the plasmonic devices [1]. Plasmonic materials are referred for the generation, enhancement, confinement, and propagation of SPPs [2]. When light interacts with these plasmonic materials, excitation of SPPs occurred with the incident wavelength comparable with the dimensions of the Anam Ahmad, Tahir Iqbal, and Almas Bashir equally contributed to this work * Tahir Iqbal [email protected] * Almas Bashir [email protected] 1
Department of Zoology, Faculty of Science, University of Gujrat, Hafiz Hayat Campus, Gujrat 50700, Pakistan
Department of Physics, Faculty of Science, University of Gujrat, Hafiz Hayat Campus, Gujrat 50700, Pakistan
2
material [3]. Refractive index (RI) determines the optical property of any plasmonic material [2]. The concept of plasmonic based biosensing was first given by Leidberg et al. till 1983 for gas sensing and for antigen-antibody recognition [4]. The dispersion relation is the mathematical treatment for the generation of SPPs on dielectric-metal interface [5]. As the wave vector of SPPs is greater than the wave vector of the inciden
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