Precise compensation of fiber group delay in coherent optical fiber communications

A group delay in an optical fiber is one of the major factors limiting the transmission distance of a long-distance, high bit-rate optical fiber communication system using in-line erbium doped fiber amplifiers (EDFAs). The group delay can be compensated by a delay equalizer (a stripline section, for instance) inserted in the intermediate frequency stage of a coherent receiver. The purpose of this paper is to propose a method for compensating the fiber group- delay precisely by adjusting the width distribution of a nonuniform, open-type stripline compensator and thus optimizing its group-delay characteristics. It is shown that, by using the optimized nonuniform stripline, the overall group-delay dispersion is reduced to approximately 1/20 of the value obtained with an ordinary, uniform stripline compensator. The effectiveness of the optimized stripline was confirmed by a computer simulation of the entire system.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.