Design and analysis of a photonic crystal fiber sensor for highly toxic gases detection Mohammad Abrar Nasif, Farhan Shahriyar, Md Mujahid Hossain, Abdul Gafur and Rakibul Hasan Eur. Phys. J. Plus, 140 1 (2025) 22 Published online: 11 January 2025 DOI: 10.1140/epjp/s13360-025-05967-0