Design and analysis of a photonic crystal fiber sensor for highly toxic gases detection

This paper describes a photonic crystal fiber (PCF) sensor designed to detect toxic gases in the THz frequency range. The proposed sensor demonstrates exceptional performance characterized by low confinement loss, minimal effective material loss, and high relative sensitivity across various gas types, including benzene (C₆H₆), methyl bromide (CH₃Br), sulfur trioxide (SO₃), tin (IV) chloride (SnCl₄), and vinyl chloride (C₂H₃Cl). Several crucial parameters of the proposed PCF were investigated throughout a broad THz spectrum ranging from 0.4 to 2.0 THz. To quantify the performance of the proposed fiber sensor, the finite element method (FEM) framework is used. The confinement loss is observed to be as low as 10^–19 dB/cm ensuring efficient light propagation and minimal leakage for accurate gas detection. A comprehensive analysis of the sensor’s performance reveals that it achieves a high relative sensitivity for methyl bromide which is 99.068%, low effective material loss of 0.013163 cm⁻¹, larger effective area of 3.0683 μm², core power fraction of 92.294%, low confinement loss of 1.67 × 10^–19 dB/cm, and high nonlinearity of 2.459 × 10^–09. The other toxic gases, such as benzene, tin (IV) chloride, sulfur trioxide, and vinyl chloride also showed very gratifying results with relative sensitivity of 98.464, 97.987, 98.729, and 98.516%, low effective material loss of 0.005516, 0.0048967, 0.014494, and 0.01522 cm⁻¹, and core power fraction of 96.677, 97.033, 91.53, and 91.112%. The sensing principles discussed provide a simple and effective way for detecting gases, making them appropriate for a variety of gas sensing applications.