A High‐Resolution THz‐PCF Sensing Framework: Precise Identification of Food Preservatives Through Refractive Index Analysis

ABSTRACT This work proposes a new terahertz (THz) photonic crystal fiber (PCF) sensor with an analyte‐filled core for detecting hazardous food preservatives. It involves a polygonal core that acts as a sensor medium with a cladding portion consisting of air slots that are radially positioned to ensure enhanced confinement of electromagnetic fields and efficient interaction with light and analyte. This research uses potassium sorbate, sodium benzoate, and calcium propionate as sample analytes because these preservatives have similar refractive indices and are commonly used in foods. This study utilizes RI changes in the core filled with analyte for sensing. Numerical analysis will be performed using the FEM in COMSOL Multiphysics with a very fine mesh. Simulation is done at an operating wavelength of 2 THz, where good performance is observed. The maximum relative sensitivity values of 99.3556%, 99.2561%, and 99.1417% were obtained for calcium propionate, sodium benzoate, and potassium sorbate, respectively. Additionally, calcium propionate has been found to have the lowest confinement loss (2.51 × 10 ^{− 9} cm ^{− 1} ), NA (0.2775), AE (8.854 × 10 ^{− 8} m ² ), and material loss (0.00225 cm ^{− 1} ).These findings highlight the proposed PCF sensor as a highly sensitive and efficient platform for advanced food safety monitoring applications.