Extremely Dispersive Fiber With Gradient-High-Index Core and Concentric Ring

In this work, an extremely dispersive optical fiber, incorporating a gradient-index central core and extra concentric ring structure of high-index material, is proposed and tailored specifically for the HE1,1 mode. The impacts of geometrical parameters and doping concentration are explored for the corresponding dispersion characteristics. By systematically adjusting diverse fiber parameters, it becomes evident that alterations in the curve slope discrepancies between the effective index of the central core and the outer ring directly influence both the optical dispersion peak and bandwidth. Consequently, the optical dispersion characteristics of the designed fiber can be customized to meet specific requirements by adjusting both fiber geometry and doping concentration of germanium dioxide. Further refinement of the fiber’s geometric parameters results in achieving a negative chromatic dispersion value of -203,898 ps/(nm $\cdot $ km) at 1547.9 nm. Moreover, the peak dispersion magnitude in our gradient-index fiber design significantly surpasses that of the step-index fiber.