Reduction of pattern-effect in high-speed XGM-based all-optical switches using two-cascaded SOAs

Two-cascaded bulk semiconductor optical amplifiers (SOAs) with different bandgaps are proposed as a high-speed all-optical switch based on cross-gain-modulation (XGM) to mitigate the pattern-effect inflicted by a carrier-lifetime-related long-lived gain recovery tail. We numerically analyze the ultrafast gain dynamics in such setup excited by 100 Gbit/s pseudorandom return-to-zero control signal over broad spectral region. The simulation results indicate that the pattern-effect in a SOA in which control pulses is localized in gain region can be reduced by a concatenated SOA in which control pulses is situated in absorption region. This compensation principle is always valid even when bit-rate is beyond 100 Gbit/s, as long as intraband transitions are utilized as XGM mechanism.