Enhancement in performance of an evanescent wave fiber optic sensor in the near-infrared region by graphene’s chemical potential

Abstract

An intensity interrogation-based fiber optic evanescent wave sensor with graphene monolayer is simulated and analyzed in the near-infrared spectral region. Chalcogenide glasses are considered as fiber’s core and clad materials. Dispersion relations of normal and malignant human liver tissues are considered for analysis. The effect of graphene’s chemical potential (μ) on sensor’s performance is examined, which is evaluated in terms of sensitivity and resolution. The analysis of simulation results indicates that if μ is set around 0.45 eV at 1550-nm light wavelength (λ), the sensitivity achieved is nearly 47 mW/RIU (real index) and 280 mW/RIU (imaginary index), and the resolution achieved is of the order of 10−9 RIU (real index) and 10-10 RIU (imaginary index). Even further improvement in the sensing performance can be achieved around μ = 0.6 eV. The analysis shows that it is preferable to use p-polarized light as it provides significantly better values of sensitivity and resolution than s-polarized light. In addition to smaller photodamage and reduced Rayleigh scattering (due to being operated in NIR), the proposed fiber optic sensor probe has the capability to provide considerably superior resolution than existing fiber optic sensors based on different techniques.