Computational Modeling of D-shaped Optical Fiber Nitrate and Sulfate Sensor

Sulfates and nitrates are ions that are present in many important chemical processes such as the manufacture of fertilizers. This work proposes the use of single-mode D-shaped optical fiber (SMF-D) as an optical sensor platform to measure the concentration of these ions. Computational modeling, exploring the finite element method, was explored in the evaluation of the fiber sensor performance, considering ammonium nitrate and ammonium sulfate, with 10%, 25% and 40% concentrations, in water solution. The SMF-D sensor showed higher performance for a configuration with no residual cladding and D-shaped region length of 25 mm. The proposed optical sensor presents a sensitivity of 0.0016 dB/% for ammonium nitrate solutions and 0.0015 dB/% for ammonium sulfate solutions.