Advanced Terahertz Sensing of Liquid Petrochemicals: Pentagonal‐Core Photonic Crystal Fiber Design and Performance

Using the terahertz band, a hybrid‐structured photonic crystal fiber using a pentagonal core is developed and also evaluated to determine fuel adulteration level. The finite element method (FEM) solver within COMSOL software is employed to assess the suggested sensor's activity. The suggested sensor outperforms this experiment at 2 THz, demonstrating an incredibly high relative sensitivity of 98.20% for diesel, 97.52% for kerosene, and 96.58% for petrol. Comparably, confinement loss is smaller than those reported in previous research, i.e., 4.88 × 10 ⁻¹³ dB/m for diesel, 9.46 × 10 ⁻¹³ dB/m for kerosene, and 9.46 × 10 ⁻¹⁴ dB/m for petrol. Additionally, the significant effective area is 6.50 × 10 ⁻⁰⁸ m ² for diesel, 6.68 × 10 ⁻⁰⁸ m ² for kerosene, and 6.13 × 10 ⁻⁰⁸ m ² for petrol, and the little effective material loss (EML) is 4.9 × 10 ⁻⁰³ cm ⁻¹ for diesel, 5.8 × 10 ⁻⁰³ cm ⁻¹ for kerosene, and 6.9 × 10 ⁻⁰³ cm ⁻¹ for petrol. We firmly believe that the hybrid air holes included in the proposed optical sensor's optimized geometrical structure ensure reduced complexity during fabrication. Petrochemical sensors are essential to many industries, such as food, oil, and agriculture.