Propagation characteristics of single-mode optical fibers with arbitrary complex index profiles: a direct numerical approach

We present here a rapidly converging numerical procedure for the evaluation of the propagation characteristics of a single-mode optical fiber with an arbitrary complex refractive index profile. To illustrate the procedure, we have first applied it to a fiber with a complex step index profile. As an application, we have used it to evaluate the gain in a typical 980-nm pumped erbium-doped fiber.