Abstract

A tapered optical fiber sensor with four arrangements of gold nanoparticles (Au NPs) on its waist is simulated and the fiber transmittance by changing the analyte refractive index (RI) is obtained. The method is a combination of the finite-difference time-domain method and the finite element method. The effect of NPs on top of each other and dimers is investigated, which is the first step in studying the aggregation of NPs in the cluster NP model. In addition, the effects of fiber diameter, NP diameter, and fiber length are examined. It is shown that by variation of NP arrangement, the amplitude sensitivity increases from 1.5 per refractive index unit (${{\rm RIU}^{- 1}}$) to ${4.53}\;{{\rm RIU}^{- 1}}$ and the wavelength sensitivity increases from 58.24 to 116.74 nm/RIU. The dimensions of the structures and the ranges of analyte RIs are in the field of practical biosensors, to be close to reality and to be effective in diagnosing diseases.

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