All optical XOR, AND, OR, and, NOR functionality has been demonstrated experimentally using
semiconductor optical amplifier (SOA) based devices at 40 Gb/s, 80 Gb/s. The performance of
the optical logic operations has been analyzed by solving the rate equation of the SOA
numerically. The high-speed operation is limited by the gain and phase recovery times in the
SOA. In order to solve these limitations, a differential scheme for XOR operation has been
experimentally investigated. This scheme is potentially capable of XOR operation to > 100 Gb/s.