<title>Modeling direct detection and coherent-detection lightwave communication systems that utilize cascaded erbium-doped fiber amplifiers</title>

Abstract

A theoretical model has been applied to predict the performance of lightwave communication systems which incorporate cascaded erbium-doped fiber amplifiers (EDFAs). The model has been applied to direct and coherent detection systems. We have used the model to predict the performance of new direct-detection system configurations which demonstrate the limits of bandwidth x length products which can be obtained in future experimental systems. We have carried out a sensitivity analysis of direct and coherent lightwave communication systems incorporating EDFAs to variations in critical system parameters. These include: optical bandwidth electrical bandwidth bit-rate spontaneous emission factor fiber chromatic dispersion number of cascacTed EDFAS splice efficiency and source laser linewidth. We have also developed a model for a direct-detection system which uses distributed erbium-doped fiber amplifiers (DEDFAS) and used the model to predict the performance of such a system. Results indicate that a high Signal-to-Noise Ratio (SNR) ratio can be maintained throughout the system if the gain per unit length is held at a fairly low level. Compared with a " lumped" amplifier approach we find that the distributed fiber amplifier approach yields a 14 dB improvement in SNR.