Numerical investigation of wide geographical transport networks based on 40 Gb/s transmission with all optical wavelength conversion

In this work, we report an investigation on 40 Gb/s transmission performance in the presence of all optical wavelength converters based on four wave mixing in semiconductor optical amplifiers and on difference frequency generation in periodically poled Litium Niobate waveguides. Both these devices permit wavelength conversion with high performance in 40 Gb/s signal transmission in terrestrial links, even though, in the case of litium niobate waveguides the distances can be much longer and a higher number of wavelength converters can be located along the link. This is due to the fact that periodically poled litium niobate waveguides can be assumed as an ideal device, while the semiconductor optical amplifier, due to its lower efficiency and higher noise level, induces higher signal degradation. Using the results of the transmission performance of 40 Gb/s lighpaths, we show how to obtain a wavelength assignment in a wide geographical transport network, connecting the main cities of Europe, when all optical wavelength converters are introduced in the network nodes. These results show that transport networks can now use wavelength conversion if it is based on periodically poled litium niobate waveguides and such converters can be located in the nodes without adding relevant degradation in the signal transmission.