Abstract
Nerve agents such as Sarin, Soman, and Tabun are among the most lethal chemical warfare agents, classified as mass destruction agents due to their extreme toxicity and rapid disruption of the nervous system. These highly volatile and easily dispersible compounds can be deployed in warfare or acts of terrorism, causing fatal respiratory failure, seizures, and irreversible nerve damage even at minimal exposure. The urgency of detecting these agents with high precision is critical for global security and counterterrorism efforts. To address this challenge, a highly sensitive photonic crystal fiber (PCF) sensor with an elliptical cladding and circular core (E-PCF) is designed for the rapid and accurate detection of nerve agents in the terahertz (THz) spectrum. The sensor employs circular air holes in the vestibule region to enhance light-matter interaction, optimizing detection through key performance metrics such as relative sensitivity, effective material loss, and confinement loss. Using two materials, such as silica glass and Zeonex as background materials, the proposed sensor demonstrates exceptional sensitivity and minimal loss. Numerical analysis within the 1.6-3.6 THz range reveals outstanding performance for Sarin (99.6% relative sensitivity, 3 × 10⁻(13) dB/m confinement loss), Soman (98.8% relative sensitivity, 1.1 × 10⁻¹² dB/m loss), and Tabun (98% relative sensitivity, 7.6 × 10⁻(11) dB/m loss). With its exceptional optical properties, silica glass ensures highly reliable detection, making the proposed sensor a powerful tool for counterterrorism efforts, environmental monitoring, industrial hazard detection, and military defense. This innovative PCF-based sensing technology marks a major breakthrough in chemical warfare agent detection, providing a fast, precise, and efficient solution for identifying highly toxic substances that pose severe threats to public safety and national security.