Modeling of Distributed Nonlinear Optical Amplification in Truewave and G.652 Telecommunication Fibers

Abstract

Common techniques for modeling of the nonlinear optical amplifiers, specifically based on the effect Raman effect, despite the simplicity of its technical implementation, are quite complex and cumbersome due to the necessity of theoretically describing the nonlinear interaction of many pump and signal optical waves using the corresponding systems of high-order differential equation. The fundamental limitations of such methodologies lie not only in the number of equations but also in the existence of special points in each equation describing the dynamics of signal waves (these points correspond to threshold values of pump power). Under these conditions, the solutions instabilities of the differential equations and their ambiguity sometimes have a detrimental impact on modeling results. An alternative modeling approach using the specified pump approximation requires particular investigations of its practical applicability to the analysis of distributed optical amplification in telecommunications fibers. Therefore, there is a need to determine the criterion for the applicability of the specified pump approximation for the development of a simplified model of nonlinear optical signal amplification under the conditions of their propagation along standard silica fibers. Among the undeniable advantages of analytical solutions obtained based on the simplified model there is the elimination of the mentioned constraints of solving systems of many differential equations. This article is devoted to modeling the dynamics of distributed Raman amplification, as function the length of standard single-mode optical fiber (SMF) and pump power. In justifying the proposed modeling methodology, it is shown that the parameters of active fibers and fiber Raman amplifier (hereinafter referred to as FRA) schemes correspond to the criterion for the applicability of the specified pump approximation. The paper presents an analytical expression for the criterion of the applicability of the specified pump approximation in the form of an upper limit of the signal power, which cannot exceed the amplified signal. Comparative analysis results of the distributed FRA parameters depending on the length of active fibers, such as G.652 and TrueWaveRS, are presented.