Using the cross-gain modulation (XGM) characteristics of semiconductor optical amplifiers (SOAs), multi-functional all-optical logic gates, including XOR, AND, and OR gates are successfully simulated and demonstrated at 10Gbit/s. A VPI component maker^TM simulation tool is used for the simulation of multi-functional all-optical logic gates and the10 Cbit/s input signal is made by a mode-locked fiber ring laser. A multi-quantum well (MQW) SOA is used for the simulation and demonstration of the all-optical logic system. Our suggested system is composed of three MQW SOAs, SOA-1 and SOA-2 for XOR logic operation and SOA-2 and SOA-3 for AND logic operation. By the addition of two output signals XOR and AND, all-optical OR logic can be obtained.