Semiconductor optical amplifier space switch BER improvement and guard-time reduction through feed-forward filtering

Analysis of the guard-time interval impact on bit error rate (BER) of a linear SOA-based space switch aiming the guard-time reduction is presented, including effects of fiber propagation. The characterization employed feed-forward filtering and optical switching techniques, through several types and lengths of fibers (with and without dispersion compensation). The Wiener filter (with 2 taps) consistently showed a switching performance improvement, with a guard-time (GT) reduction enough to achieve the BER pre-FEC limit. In most configurations the average GT was of 429ps (3 bits GT at 7Gbps). The overall best GT result achieved was using 100mA of SOA bias current and applying the Wiener Filter, resulting in a GT of 286ps (2 bits GT at 7Gbps). The space-switch operating parameters with focus on the bias current and switching technique configuration were also analyzed, aiming at reducing the SOA-based electro-optical space switch guard-time, allowing the achievement of high commutation rates.