Powerful solution for simulating nonlinear coupled equations describing bidirectionally pumped broadband Raman amplifiers

A mid-point shooting algorithm using the Newton-Raphson method is adopted for solving nonlinear coupled equations describing bidirectionally pumped broadband Raman amplifiers. A series of novel backward-differentiation methods are constructed for the first time to our knowledge. Their combination can form a powerful solution for fiber amplifiers. Numerical results show that the approach can solve Raman amplifier propagation equations on various conditions including co-, counter-, and bidirectionally pumped cases. The computation speed of the present methods is about four times that of the backward-differentiation methods previously adopted. (C) 2004 Optical Society of America.