New refractive index profiles of dispersion-flattened highly nonlinear fibers for future all-optical signal processing in wdm optical networks

Abstract

In this paper, we demonstrate new dissimilar refractive index profiles for highly nonlinear ultra-flattened dispersion fibers with noteworthy effective area (A eff ) for future optical signal processing. The newly proposed fibers named from Type 1 to Type 5 have a flattened dispersion over S, C, L and U bands. Predominantly, few-mode HNL-UFF fiber of Type 3 yields dispersion-flattened characteristics over a range of 250 nm of optical communication spectrum with a mere 0.2 ps/nm km variation in dispersion and a dispersion slope of 0.0057 ps/nm 2 km due to the contribution of higher-order modes to the dispersion characteristics of the fiber. Moreover, it has a moderate nonlinear coefficient of 8.03 W −1 km −1 . By modifying the refractive index profile of Type 3 fiber, Type 4 and Type 5 fibers are obtained in order to ensure single-mode operation, while the zero flattened dispersion characteristics of the fiber are compromised. Among the newly proposed fibers, Type 4 fiber offers a very low ITU-T cutoff wavelength of 1.33 µm, whereas in the case of Type 5 fiber it is 1.38 µm. Moreover, Type 4 and Type 5 fibers have good nonlinear coefficients of 12.26 W −1 km −1 and 11.45 W −1 km −1 , respectively. By virtue of the proposed optimized index profile, an insensitive behavior toward bending is displayed by Type 3, Type 4 and Type 5 fibers. In addition, Type 4 fiber provides a better splice loss of 0.25 dB.Keywords Highly nonlinear ultra-flattened dispersion fiber (HNL-UFF) · Zero-dispersion wavelength (ZDW) · Refractive index profile · Effective area (A eff ) · Dispersion · Dispersion slope · Wavelength conversion (WC) B S. Selvendran