Analysis of tunable wavelength converters based on cross-gain modulation in semiconductor optical amplifiers operating in the counter propagating mode

A detailed theoretical study is presented on wavelength conversion using cross-gain modulation in SOAs, employing counter-propagation of the input and the probe signals. The Fabry-Perot resonances caused by the residual facet reflectivities of the device are considered. Theoretical and experimental results on the performance of the converter, in terms of extinction ratio, crosstalk and conversion bandwidth, are presented and discussed. Good agreement between theoretical and experimental results has been observed. The concatenation performance of a simple WDM optical cross-connect architecture employing this type of wavelength converter is experimentally investigated using a re-circulating loop. Penalty-free concatenation of 25 such nodes has been demonstrated