The cross-phase modulation in erbium-doped fiber amplifiers

The nonlinear Schroedinger equation (NLSE) in erbium-doped fiber (EDF) is o btained. Based on this NLSE, a more generalized form of the propagation equ ation in the erbium-doped fiber amplifiers (EDFA) is given which has includ ed the phase shift that the erbium ions induce. The cross-phase modulation (XPM) in the EDFA is studied according to that erbium ions induced phase sh ift. An analytical expression is given to the frequency chirp that the dope d-erbium ions induce. It was found that the frequency chirp dose not change much with the wavelength except at the neighbouring wavelengths (around 1. 531 mu m) where absorption and the emission cross-sections of the erbium io ns reach their maximum, and the frequency chirp has opposite sign on the tw o sides around 1.531 mu m. Furthermore, it was found that the frequency chi rp will increase with increasing length of the EDF. (C) 2000 Elsevier Scien ce B.V. All rights reserved.