Theoretical investigation of physical parameters measurements of a liquid in a vessel using optoelectronic oscillators

Real-time access to the physical parameters of a liquid such as temperature, refractive index, and depth in a vessel could contribute to preserving the quality of the liquid. In this study, the optoelectronic oscillator-based measurement of these physical parameters is discussed. The refractive index, the temperature, and the depth of the liquid are translated into a variation in the oscillation frequency of the optoelectronic oscillators. For the temperature and refractive index, the phase-shifted fiber Bragg grating immersed in the liquid acts as a sensor. Contrariwise, the depth measurement of the liquid is achieved through the round-trip flow of the light in the vessel. Using appropriate values of the system parameters, the theoretical sensitivities for the temperature and depth were reported as 283 MHz/°C and 421.94MHz/cm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$421.94\, \text{MHz/cm}$$\end{document}, respectively. It is also noticed that when tuning the cubic-nonlinear parameter, the cubic-nonlinear optoelectronic oscillator significantly increases the measurement sensitivity.