Pulse shape evolution and noise estimates in concatenated fiber links using analog optoelectronical repeaters

The pulse shape evolution in a chain consisting of dispersive fiber segments concatenated by analog optoelectronical repeaters is investigated. Analytical results based on a linear propagation model and Gaussian pulse shape with linear chirp as well as more realistic simulations, taking into account different pulse shapes and fiber nonlinearities, show that analog optpelectronical repeaters allow a significant improvement in the dispersion accumulation along the chain compared with all-optical amplification. To transmit data sequences, return-to-zero modulation has to be applied and simulations show that 10 Gb/s data can be transmitted at least over a distance of 1000 km with an power penalty caused by dispersion of 0.7 dB only. However, the noise accumulation reduces this length. For sufficiently large number of fiber segments with realistic parameters, the all-optical amplification performs better from a noise point of view.