Field demonstration of 40 Gb/s soliton transmission with alternate polarizations

A 40-Gb/s single-channel soliton transmission was performed on a dispersion -shifted fiber (DSF) embedded in a link connecting Rome to Pomezia. The sol iton system was based on the transmission of pulses with orthogonal states of polarization (alternate polarizations) to limit the impairments due to t he soliton interaction. The performance of the system operating in the held has been compared with results obtained in the laboratory, While in the la boratory the system showed a nearly-stable error-free transmission over 700 km, strong temporal fluctuations of the performance have been observed in the field trial. Numerical simulations have shown that such a degradation, and in particular the fluctuation of the Q factor, is mainly due to a polar ization mode dispersion of the installed tables larger than that of the fib ers used in the laboratory. However, 500 km error-free transmission was obs erved in the field for time interval longer than one hour, demonstrating th e potentiality of a 40 Gb/s soliton system with alternate polarizations ope rating with long amplifier spacing (100 km) without in-line control.