A nearly-zero ultra-flattened dispersion photonic crystal fiber: Application to broadband transmission platforms

This paper reports a novel design in photonic crystal fibers (PCFs) with nearly zero ultra-flattened dispersion characteristics. We propose a method to control the chromatic dispersion properties of PCFs by the small change of the innermost rings pitch and its size. Through inward and outward optimizing innermost ring, nearly-zero ultra-flattened dispersion PCFs can be efficiently designed. It is shown that nearly zero dispersion values between 0 ± 0.22 [ps/(nm-km)] can be achieved over S + C + L wavelength bands with confinement losses of less than 10^-8dB/km. Macro-bending loss performance of the design PCF is also studied and it is found that the fiber shows extremely low bending losses for the smallest feasible bending radius of 5mm. Finally, we point out that full controllability of the chromatic dispersion and confinement losses as well as simple structure design are the main advantages of the proposed PCF.