A simple but accurate method for study of radial variation of pump and signal intensities in single-mode erbium-doped dispersion-shifted as well as dispersion-flattened fiber amplifier

The doped fiber amplifier provides broadband amplification in case of multi-channel optical signals in long-haul communication systems. In this context, single-mode dispersion-shifted and dispersion-flattened fibers have emerged as potential candidates for the purpose of communication of information through fundamental mode. Consequently accurate but simple expression for the fundamental modal field in the doped fiber, both for the pump and the signal as well, is important for investigation of their variations with radial distance. Employing the simple but accurate power series expression of fundamental modal field for dispersion-shifted trapezoidal and dispersion-flattened step and graded W fibers, we estimate how the modal intensity changes with change of radial distance from the axis of such type of fiber in case of both the pump and signal intensities. Using some typical fibers of the said kind as examples, we show that our estimations by this simple formalism agree excellently with the numerical exact results. Our method requires little computations for the concerned calculations. Prescription of such simple but accurate formalism will benefit the system engineers who are working in the field of all optical technology.