Particle Swarm Optimization and Finite-difference Time-domain Algorithms for Gas Sensors Based on Photonic Crystal Fiber

In this paper, a gas detection sensor based on photonic crystal fibers with high sensitivity and low loss is designed and optimized for the detection of two gases, namely carbon tetrachloride (CCl₄ , n=1.461) and tin tetrachloride (SnCl4, n = 1.5086). The finite-difference time-domain (FDTD) method is used to simulate light propagation in the PCF. By applying the PSO algorithm and optimizing the geometric dimensions of the photonic crystal fiber, including the core diameter, hole diameter, and lattice constant, very low losses are achieved, resulting in higher relative sensitivity. The numerical simulation results demonstrate that the designed sensor has a sensitivity coefficient of 70.2% and 77.3% for CCl₄ and SnCl4 at a wavelength of 2.6 µm, respectively. It also exhibits very low losses (in the range of 10-8dB/cm) compared to other studies. This sensor is a suitable tool for detecting toxic gases in industries such as chemical manufacturing, environmental monitoring, and occupational health and safety, with absorption in the spectral range of the bandgap from 1 to 3µm.