A Novel Numerical Algorithm for nth-order Cascaded Raman Fiber Lasers Based on Genetic Algorithm and Shooting Method

摘要

In this paper, we proposed a novel numerical algorithm for nth-order cascaded Raman fiber lasers (CRFLs) with the combination of genetic algorithm (GA) and shooting method. Although shooting method possesses fast speed in solving nonlinear two-point boundary-value ordinary differential equations, calculating process may diverge if it is directly applied in the coupled equations of CRFLs when arbitrarily guessed initial values are out of the domain of convergence. To overcome the problem, genetic algorithm which has rather strong searching ability in global space is firstly employed to search for the initial value in convergent domain for each Stokes power; and then, the task of finding the more accurate initial values is finished by shooting method instead of GA whose searching ability is weak in local region. As an example, a sixth-order Ge-doped CRFL has been simulated by the novel algorithm. Calculated results show that the new method can effectively and quickly solve the coupled equations of the CRFL without the problem of divergence.