Highly Nonlinear Dispersion-Shifted Fibers and Their Application to Broadband Wavelength Converter

Abstract

Highly nonlinear dispersion-shifted fibers were designed and fabricated for efficient nonlinear effect generation. High-concentration GeO2-doped core and fluorine-doped cladding were employed in this study, and the fabricated fiber successfully realized a high nonlinear coefficient of 20.4 W−1km−1and a low attenuation of 0.51 dB/km. Using the fabricated fiber, four-wave mixing (FWM) generation was demonstrated aiming at its application to wavelength conversion, and its efficiency, which was defined as the ratio of the FWM product to the input signal power, was dramatically improved to about 60 times higher than that with the conventional dispersion-shifted fibers. The enhanced conversion efficiency allows the required fiber length to be shortened, and this is also beneficial to reduction of the overall zero dispersion wavelength fluctuation, which contributes to broadband wavelength conversion. The fabricated fiber shorter than 500 m exhibited efficient generation of FWM, and a nearly constant wavelength conversion efficiency over 20 nm, which covers most of the erbium-doped fiber amplifier gain bandwidth, was successfully demonstrated.