An all-optical XOR logic gate for phase-modulated (PM) or amplitude-modulated (AM) signals is proposed. It achieves XOR operation by direct interference of light. Through simulation, this scheme is proved to be effective for XOR operation of PM or AM signals at 10 Gb/s. When the inputs are AM signals of which the duty cycle is less than 0.4 and the peak powers are equal, the Q factor of XOR output is 103. When the inputs are PM signals with π phase modulation depth, the Q factor of XOR output is 272.