Emphasis on sensitivity and accuracy: Design and optimization of a high-sensitivity terahertz photonic crystal fiber sensor for precision analysis of petrochemical-based adulterants in hydrocarbon mixtures

Abstract

This study introduces an innovative octagonal cladding with hollow-core photonic crystal fiber (PCF) sensor designed for the identification of kerosene adulteration within the terahertz (THz) spectral domain. The sensor's performance is rigorously assessed through simulations conducted using COMSOL Multiphysics, a high-fidelity platform based on the finite element method (FEM) for analyzing complex electromagnetic behaviors within the fiber structure. The sensor's performance was estimated throughout numerical simulations across frequencies varying from 1.0 to 3 THz. Simulation results demonstrate that the optimized design achieves an outstanding relative sensitivity of 97.20% at a target frequency of 2.2 THz, markedly surpassing the capabilities of existing sensing technologies. Moreover, the sensor exhibits extremely low confinement loss, measured at 6.08 × 10⁻⁸ dB/m, along with a minimal effective material loss of 0.00654 cm⁻¹. These characteristics enable the precise detection of minute refractive index differences associated with the unique chemical profiles of various petroleum-based fuels. The high sensitivity and low-loss performance of the proposed sensor support non-invasive and non-destructive testing, ensuring that the samples remain unaltered during analysis. The exceptional sensitivity and accuracy of the proposed sensing system position it as a highly effective solution for detecting kerosene adulteration, thereby safeguarding the quality of petroleum-based fuels for end users. Furthermore, advanced fabrication methods such as extrusion and additive manufacturing may be utilized to produce the photonic crystal fiber-based sensor with enhanced structural precision and scalability.