Geometric Optimization and IPA-Induced Dispersion Tuning in Solid-Core Photonic Crystal Fibers

This study presents a comprehensive numerical investigation of solid-core photonic crystal fibers (PCFs) with circular and hexagonal cladding geometries, aiming to optimize key optical parameters for nonlinear photonics and environmental sensing applications. Full-vectorial simulations using FDTD (Lumerical), PWE (MPB), and FDE (MODE) are employed to analyze the influence of structural parameters—core diameter (d_c), pitch (Λ), and air filling fraction—on zero-dispersion wavelength (ZDW), nonlinear coefficient (γ), effective mode area (A_eff), and confinement loss. The results reveal that decreasing d_c from 2.4 µm to 1.4 µm enables ZDW tuning from 791 nm to 646 nm, alongside a 72% increase in γ, from 72 W⁻¹ km⁻¹ to 124 W⁻¹ km⁻¹. The impact of isopropyl alcohol (IPA) infiltration is also examined, demonstrating a significant red-shift in ZDW and reduced index contrast that deteriorates confinement and dispersion slope. These findings establish a robust design framework for PCFs that combines high nonlinear efficiency with resilience against contamination, offering valuable guidance for supercontinuum generation and chemical sensing applications.