Analysis and Simulation of a Novel Localized Surface Plasmonic Highly Sensitive Refractive Index Sensor
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Analysis and Simulation of a Novel Localized Surface Plasmonic Highly Sensitive Refractive Index Sensor Hamid Bahador 1
&
Hamid Heidarzadeh 1
Received: 4 December 2019 / Accepted: 17 February 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract Dividing a metal nanoparticle into smaller components and the occurrence of the plasmonic phenomenon in the gap between these components can improve the sensitivity of the detector to variation of the refraction coefficient of liquid. In this paper, in a constant volume of metal, a golden disk is divided into two rings and one smaller disk. With a proper arrangement of these components, the surface plasmon resonance phenomenon takes place at the wavelength of 945.7 nm. The occurrence of this phenomenon increases the field in the distance between nanoparticles surrounded by liquid. The sensitivity of the detector that designed using nanodisks is 300 nm/RIU while it increases to 500 nm/RIU for the new structure. The increase of LSPR displacement, for a variation of 0.01 in the liquid refraction coefficient, from 3 nm for a disk to 5 nm for a proposed structure verifies a 67% improvement in the sensitivity of the sensor. Keywords Plasmon . Refractive index sensor . Plasmonic effects . Nanodisks
Introduction Plasmonic metal nanostructures play a pivotal role as the main components of optical sensors, which have a wide variety of applications ranging from illness diagnosis to detecting environmental conditions [1–3]. Plasmonic waves are created through scattering from a conducting nanoparticle whose dimensions are below the wavelength of the electromagnetic field of the exciting beam [4–6]. Due to the occurrence of localized surface plasmon resonance in metal nanostructures, variations in the wavelength and intensity of absorption peak can be used to detect the variations of refraction coefficients of liquids [7–9]. Sensitivity to variations of the refraction coefficient is one of the important parameters for evaluating the performance of optical detectors. Realization of the conditions in the nanostructure of surface plasmons under which the frequency of the photons of the radiated beam becomes the same as the natural frequency of surface electrons improves the sensitivity of the detector. Size, shape, material, geometry, and the
* Hamid Bahador [email protected] 1
Department of Electrical and Computer Engineering, University of Mohaghegh Ardabili, Ardabil, Iran
distance between nanoparticles are the parameters that determine the frequency and possibility of occurrence of surface plasmon resonance phenomenon in a wide range of visible and near-infrared light beams [10]. Gold and silver are the most commonly used materials in these detectors. Local surface plasmon resonance (LSPR) is the coupling of the free electron collective oscillation of metal nanoparticles and incident photons [11–13]. When the surface electron oscillation and the photon vibration form a resonance, the nanoparticle will strongly absorb the photon energy, and the L
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