Performance comparison of uniform and graded photonic crystal fibers for dispersion-managed optical transmission

Abstract In this work, a detailed numerical comparison between uniform and graded photonic crystal fibers (PCFs) is presented under strictly identical geometrical, material, and numerical conditions. The graded PCF is realized through radial modulation of air-hole diameters in the cladding, while the uniform PCF employs identical air holes throughout. Finite element simulations are carried out using COMSOL Multiphysics over a broad wavelength range of 0.8–1.8 μm, covering major optical communication bands. Key waveguiding characteristics including effective refractive index, chromatic dispersion, effective mode area, mode field diameter, nonlinear coefficient, core power fraction, and confinement loss are systematically analyzed. The results demonstrate that graded PCF exhibits significantly smoother dispersion behavior with reduced oscillations compared to the uniform design. Improved modal stability and smoother wavelength dependence of effective refractive index are also observed in the graded structure. Furthermore, graded PCF shows a larger effective mode area, leading to a reduced nonlinear coefficient, particularly at longer wavelengths. Although confinement loss slightly increases in the graded design, it remains well within practical limits. The study confirms that radial air-hole grading effectively balances dispersion control and optical confinement. These results establish graded photonic crystal fibers as promising candidates for dispersion-managed optical communication systems.