Dispersion and nonlinear characteristics of GeO₂-doped photonic crystal fiber with a hexagonal air-hole lattice

This paper presents a detailed numerical study of GeO₂-doped PCF with a hexagonal air-hole lattice structure. A central core which is doped with 20.5% germanium dioxide (GeO2) in silica is then surrounded by hexagonshaped air holes with a pitch of 2.73 µm in the fiber design. Using COMSOL Multiphysics simulations with the finite element method, we investigate the fiber’s chromatic dispersion,effective refractive index, effective mode area, and nonlinear coefficient over the wavelength range of 0.6 to 1.0 µm. According to the results which can be seen in the paper, the effective refractive index drops from 1.4697 to 1.4639 over the wavelength range under investigation, while the effective area which rises from 5.86 to 7.43 µm² . The nonlinear coefficient exhibits a decreasing trend from 1.78 × 10⁻¹¹ to 1.42 × 10⁻¹¹ W⁻¹m⁻¹ . These characteristics make the proposed fiber structure suitable for nonlinear optics, telecommunications, and supercontinuum generation.