Power transfer function of a 40-Gb/s 2R (re-amplification and reshaping) regenerator consisting of a semiconductor optical amplifier (SOA) and a delay interferometer (DI) is culculated numerically, and the regeneration performance of the SOA-DI optical gate for the degraded signals at 10~40 Gb/s is experimentally investigated. Because the cross gain modulation (XGM) effect in a SOA depends on the carrier recovery time, inverted logical signal based on XGM experiences severe pattern effect at XGM-SOA-cross gain compression (XGC) regenerator. A novel all-optical 2R regeneration scheme by combining the transient cross phase modulation and XGC effects in SOA is proposed and it successfully demonstrates all-optical 2R regeneration for 100-Gb/s return-to-zero (RZ) signal.