Ultrashort pulse train in rare earth doped bimodal optical fiber

Abstract

Here, we present and analyze the nature of a wide class of exact nonlinear wave solutions for a bimodal optical fiber doped with a three level lambda ( Λ ) type system and delineate the parameter regimes for their occurrence. Solutions that are non-resonant with the transition frequencies of the doped system are found to undergo stable propagation under numerical evolution for the small strength of atomic coherence. Higher values of coherence lead to two different behaviors of these solutions: a bound state of pulse trains for sn and cn type cnoidal waves, and amplification of pulse trains for dn type nonlinear excitations. The corresponding power spectra results in an enhanced frequency comb structure in the dominance of atomic coherence.